text: /*-------------------------------------------------------------------------
   *
   * nodeModifyTable.c
   *	  routines to handle ModifyTable nodes.
   *
   * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/executor/nodeModifyTable.c
   *
   * The following only applies to changes made to this file as part of
   * YugaByte development.
   *
   * Portions Copyright (c) YugaByte, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you
   * may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
   * implied.  See the License for the specific language governing
   * permissions and limitations under the License.
   *-------------------------------------------------------------------------
   */
  /* INTERFACE ROUTINES
   *		ExecInitModifyTable - initialize the ModifyTable node
   *		ExecModifyTable		- retrieve the next tuple from the node
   *		ExecEndModifyTable	- shut down the ModifyTable node
   *		ExecReScanModifyTable - rescan the ModifyTable node
   *
   *	 NOTES
   *		Each ModifyTable node contains a list of one or more subplans,
   *		much like an Append node.  There is one subplan per result relation.
   *		The key reason for this is that in an inherited UPDATE command, each
   *		result relation could have a different schema (more or different
   *		columns) requiring a different plan tree to produce it.  In an
   *		inherited DELETE, all the subplans should produce the same output
   *		rowtype, but we might still find that different plans are appropriate
   *		for different child relations.
   *
   *		If the query specifies RETURNING, then the ModifyTable returns a
   *		RETURNING tuple after completing each row insert, update, or delete.
   *		It must be called again to continue the operation.  Without RETURNING,
   *		we just loop within the node until all the work is done, then
   *		return NULL.  This avoids useless call/return overhead.
   */
  
  #include "postgres.h"
  
  #include "access/htup_details.h"
  #include "access/xact.h"
  #include "commands/trigger.h"
  #include "executor/execPartition.h"
  #include "executor/executor.h"
  #include "executor/nodeModifyTable.h"
  #include "foreign/fdwapi.h"
  #include "miscadmin.h"
  #include "nodes/nodeFuncs.h"
  #include "storage/bufmgr.h"
  #include "storage/lmgr.h"
  #include "utils/builtins.h"
  #include "utils/memutils.h"
  #include "utils/rel.h"
  #include "utils/tqual.h"
  #include "utils/typcache.h"
  
  /*  YB includes. */
  #include "access/sysattr.h"
  #include "catalog/pg_database.h"
  #include "executor/ybcModifyTable.h"
  #include "parser/parsetree.h"
  #include "pg_yb_utils.h"
  #include "optimizer/ybcplan.h"
  
  static bool ExecOnConflictUpdate(ModifyTableState *mtstate,
  					 ResultRelInfo *resultRelInfo,
  					 ItemPointer conflictTid,
  					 TupleTableSlot *planSlot,
  					 TupleTableSlot *excludedSlot,
  					 EState *estate,
  					 bool canSetTag,
  					 TupleTableSlot **returning);
  static TupleTableSlot *ExecPrepareTupleRouting(ModifyTableState *mtstate,
  						EState *estate,
  						PartitionTupleRouting *proute,
  						ResultRelInfo *targetRelInfo,
  						TupleTableSlot *slot);
  static ResultRelInfo *getTargetResultRelInfo(ModifyTableState *node);
  static void ExecSetupChildParentMapForTcs(ModifyTableState *mtstate);
  static void ExecSetupChildParentMapForSubplan(ModifyTableState *mtstate);
  static TupleConversionMap *tupconv_map_for_subplan(ModifyTableState *node,
  						int whichplan);
  
  /*
   * Verify that the tuples to be produced by INSERT or UPDATE match the
   * target relation's rowtype
   *
   * We do this to guard against stale plans.  If plan invalidation is
   * functioning properly then we should never get a failure here, but better
   * safe than sorry.  Note that this is called after we have obtained lock
   * on the target rel, so the rowtype can't change underneath us.
   *
   * The plan output is represented by its targetlist, because that makes
   * handling the dropped-column case easier.
   */
  static void
  ExecCheckPlanOutput(Relation resultRel, List *targetList)
  {
  	TupleDesc	resultDesc = RelationGetDescr(resultRel);
  	int			attno = 0;
  	ListCell   *lc;
  
  	foreach(lc, targetList)
  	{
  		TargetEntry *tle = (TargetEntry *) lfirst(lc);
  		Form_pg_attribute attr;
  
  		if (tle->resjunk)
  			continue;			/* ignore junk tlist items */
  
  		if (IsYsqlUpgrade && tle->resno == ObjectIdAttributeNumber)
  			continue;			/* ignore oid system column used in YSQL upgrade */
  
  		if (attno >= resultDesc->natts)
  			ereport(ERROR,
  					(errcode(ERRCODE_DATATYPE_MISMATCH),
  					 errmsg("table row type and query-specified row type do not match"),
  					 errdetail("Query has too many columns.")));
  		attr = TupleDescAttr(resultDesc, attno);
  		attno++;
  
  		if (!attr->attisdropped)
  		{
  			/* Normal case: demand type match */
  			if (exprType((Node *) tle->expr) != attr->atttypid)
  				ereport(ERROR,
  						(errcode(ERRCODE_DATATYPE_MISMATCH),
  						 errmsg("table row type and query-specified row type do not match"),
  						 errdetail("Table has type %s at ordinal position %d, but query expects %s.",
  								   format_type_be(attr->atttypid),
  								   attno,
  								   format_type_be(exprType((Node *) tle->expr)))));
  		}
  		else
  		{
  			/*
  			 * For a dropped column, we can't check atttypid (it's likely 0).
  			 * In any case the planner has most likely inserted an INT4 null.
  			 * What we insist on is just *some* NULL constant.
  			 */
  			if (!IsA(tle->expr, Const) ||
  				!((Const *) tle->expr)->constisnull)
  				ereport(ERROR,
  						(errcode(ERRCODE_DATATYPE_MISMATCH),
  						 errmsg("table row type and query-specified row type do not match"),
  						 errdetail("Query provides a value for a dropped column at ordinal position %d.",
  								   attno)));
  		}
  	}
  	if (attno != resultDesc->natts)
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("table row type and query-specified row type do not match"),
  				 errdetail("Query has too few columns.")));
  }
  
  /*
   * ExecProcessReturning --- evaluate a RETURNING list
   *
   * resultRelInfo: current result rel
   * tupleSlot: slot holding tuple actually inserted/updated/deleted
   * planSlot: slot holding tuple returned by top subplan node
   *
   * Note: If tupleSlot is NULL, the FDW should have already provided econtext's
   * scan tuple.
   *
   * Returns a slot holding the result tuple
   */
  static TupleTableSlot *
  ExecProcessReturning(ResultRelInfo *resultRelInfo,
  					 TupleTableSlot *tupleSlot,
  					 TupleTableSlot *planSlot)
  {
  	ProjectionInfo *projectReturning = resultRelInfo->ri_projectReturning;
  	ExprContext *econtext = projectReturning->pi_exprContext;
  
  	/*
  	 * Reset per-tuple memory context to free any expression evaluation
  	 * storage allocated in the previous cycle.
  	 */
  	ResetExprContext(econtext);
  
  	/* Make tuple and any needed join variables available to ExecProject */
  	if (tupleSlot)
  		econtext->ecxt_scantuple = tupleSlot;
  	else
  	{
  		HeapTuple	tuple;
  
  		/*
  		 * RETURNING expressions might reference the tableoid column, so
  		 * initialize t_tableOid before evaluating them.
  		 */
  		Assert(!TupIsNull(econtext->ecxt_scantuple));
  		tuple = ExecMaterializeSlot(econtext->ecxt_scantuple);
  		tuple->t_tableOid = RelationGetRelid(resultRelInfo->ri_RelationDesc);
  	}
  	econtext->ecxt_outertuple = planSlot;
  
  	/* Compute the RETURNING expressions */
  	return ExecProject(projectReturning);
  }
  
  /*
   * ExecCheckHeapTupleVisible -- verify heap tuple is visible
   *
   * It would not be consistent with guarantees of the higher isolation levels to
   * proceed with avoiding insertion (taking speculative insertion's alternative
   * path) on the basis of another tuple that is not visible to MVCC snapshot.
   * Check for the need to raise a serialization failure, and do so as necessary.
   */
  static void
  ExecCheckHeapTupleVisible(EState *estate,
  						  HeapTuple tuple,
  						  Buffer buffer)
  {
  	if (!IsolationUsesXactSnapshot())
  		return;
  
  	/*
  	 * We need buffer pin and lock to call HeapTupleSatisfiesVisibility.
  	 * Caller should be holding pin, but not lock.
  	 */
  	LockBuffer(buffer, BUFFER_LOCK_SHARE);
  	if (!HeapTupleSatisfiesVisibility(tuple, estate->es_snapshot, buffer))
  	{
  		/*
  		 * We should not raise a serialization failure if the conflict is
  		 * against a tuple inserted by our own transaction, even if it's not
  		 * visible to our snapshot.  (This would happen, for example, if
  		 * conflicting keys are proposed for insertion in a single command.)
  		 */
  		if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple->t_data)))
  			ereport(ERROR,
  					(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
  					 errmsg("could not serialize access due to concurrent update")));
  	}
  	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
  }
  
  /*
   * ExecCheckTIDVisible -- convenience variant of ExecCheckHeapTupleVisible()
   */
  static void
  ExecCheckTIDVisible(EState *estate,
  					ResultRelInfo *relinfo,
  					ItemPointer tid)
  {
  	Relation	rel = relinfo->ri_RelationDesc;
  	Buffer		buffer;
  	HeapTupleData tuple;
  
  	/* Redundantly check isolation level */
  	if (!IsolationUsesXactSnapshot())
  		return;
  
  	tuple.t_self = *tid;
  	if (!heap_fetch(rel, SnapshotAny, &tuple, &buffer, false, NULL))
  		elog(ERROR, "failed to fetch conflicting tuple for ON CONFLICT");
  	ExecCheckHeapTupleVisible(estate, &tuple, buffer);
  	ReleaseBuffer(buffer);
  }
  
  /* ----------------------------------------------------------------
   *		ExecInsert
   *
   *		For INSERT, we have to insert the tuple into the target relation
   *		and insert appropriate tuples into the index relations.
   *
   *		Returns RETURNING result if any, otherwise NULL.
   * ----------------------------------------------------------------
   */
  static TupleTableSlot *
  ExecInsert(ModifyTableState *mtstate,
  		   TupleTableSlot *slot,
  		   TupleTableSlot *planSlot,
  		   EState *estate,
  		   bool canSetTag)
  {
  	HeapTuple	tuple;
  	ResultRelInfo *resultRelInfo;
  	Relation	resultRelationDesc;
  	Oid			newId;
  	List	   *recheckIndexes = NIL;
  	TupleTableSlot *result = NULL;
  	TransitionCaptureState *ar_insert_trig_tcs;
  	ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
  	OnConflictAction onconflict = node->onConflictAction;
  
  	/*
  	 * The attribute "yb_conflict_slot" is only used within ExecInsert.
  	 * Initialize its value to NULL.
  	 */
  	estate->yb_conflict_slot = NULL;
  
  	/*
  	 * get the heap tuple out of the tuple table slot, making sure we have a
  	 * writable copy
  	 */
  	tuple = ExecMaterializeSlot(slot);
  
  	/*
  	 * get information on the (current) result relation
  	 */
  	resultRelInfo = estate->es_result_relation_info;
  	resultRelationDesc = resultRelInfo->ri_RelationDesc;
  
  	/*
  	 * If the result relation has OIDs, force the tuple's OID to zero so that
  	 * heap_insert will assign a fresh OID.  Usually the OID already will be
  	 * zero at this point, but there are corner cases where the plan tree can
  	 * return a tuple extracted literally from some table with the same
  	 * rowtype.
  	 *
  	 * XXX if we ever wanted to allow users to assign their own OIDs to new
  	 * rows, this'd be the place to do it.  For the moment, we make a point of
  	 * doing this before calling triggers, so that a user-supplied trigger
  	 * could hack the OID if desired.
  	 *
  	 * YB note:
  	 * --------
  	 * YSQL upgrade introduces a hacky way for INSERT to set OID implemented
  	 * via tts_yb_insert_oid. It would become obsolete after upgrade to PG 12
  	 * which would make oid a regular column.
  	 */
  	if (resultRelationDesc->rd_rel->relhasoids)
  	{
  		Oid tuple_oid = InvalidOid;
  
  		if (IsYsqlUpgrade && IsYBRelation(resultRelationDesc))
  			tuple_oid = slot->tts_yb_insert_oid;
  
  		HeapTupleSetOid(tuple, tuple_oid);
  	}
  
  	/*
  	 * BEFORE ROW INSERT Triggers.
  	 *
  	 * Note: We fire BEFORE ROW TRIGGERS for every attempted insertion in an
  	 * INSERT ... ON CONFLICT statement.  We cannot check for constraint
  	 * violations before firing these triggers, because they can change the
  	 * values to insert.  Also, they can run arbitrary user-defined code with
  	 * side-effects that we can't cancel by just not inserting the tuple.
  	 */
  	if (resultRelInfo->ri_TrigDesc &&
  		resultRelInfo->ri_TrigDesc->trig_insert_before_row)
  	{
  		slot = ExecBRInsertTriggers(estate, resultRelInfo, slot);
  
  		if (slot == NULL)		/* "do nothing" */
  			return NULL;
  
  		/* trigger might have changed tuple */
  		tuple = ExecMaterializeSlot(slot);
  	}
  
  	/* INSTEAD OF ROW INSERT Triggers */
  	if (resultRelInfo->ri_TrigDesc &&
  		resultRelInfo->ri_TrigDesc->trig_insert_instead_row)
  	{
  		slot = ExecIRInsertTriggers(estate, resultRelInfo, slot);
  
  		if (slot == NULL)		/* "do nothing" */
  			return NULL;
  
  		/* trigger might have changed tuple */
  		tuple = ExecMaterializeSlot(slot);
  
  		newId = InvalidOid;
  	}
  	else if (resultRelInfo->ri_FdwRoutine)
  	{
  		/*
  		 * insert into foreign table: let the FDW do it
  		 */
  		slot = resultRelInfo->ri_FdwRoutine->ExecForeignInsert(estate,
  															   resultRelInfo,
  															   slot,
  															   planSlot);
  
  		if (slot == NULL)		/* "do nothing" */
  			return NULL;
  
  		/* FDW might have changed tuple */
  		tuple = ExecMaterializeSlot(slot);
  
  		/*
  		 * AFTER ROW Triggers or RETURNING expressions might reference the
  		 * tableoid column, so initialize t_tableOid before evaluating them.
  		 */
  		tuple->t_tableOid = RelationGetRelid(resultRelationDesc);
  
  		newId = InvalidOid;
  	}
  	else
  	{
  		WCOKind		wco_kind;
  
  		/*
  		 * Constraints might reference the tableoid column, so initialize
  		 * t_tableOid before evaluating them.
  		 */
  		tuple->t_tableOid = RelationGetRelid(resultRelationDesc);
  
  		/*
  		 * Check any RLS WITH CHECK policies.
  		 *
  		 * Normally we should check INSERT policies. But if the insert is the
  		 * result of a partition key update that moved the tuple to a new
  		 * partition, we should instead check UPDATE policies, because we are
  		 * executing policies defined on the target table, and not those
  		 * defined on the child partitions.
  		 */
  		wco_kind = (mtstate->operation == CMD_UPDATE) ?
  			WCO_RLS_UPDATE_CHECK : WCO_RLS_INSERT_CHECK;
  
  		/*
  		 * ExecWithCheckOptions() will skip any WCOs which are not of the kind
  		 * we are looking for at this point.
  		 */
  		if (resultRelInfo->ri_WithCheckOptions != NIL)
  			ExecWithCheckOptions(wco_kind, resultRelInfo, slot, estate);
  
  		/*
  		 * Check the constraints of the tuple.
  		 */
  		if (resultRelationDesc->rd_att->constr)
  			ExecConstraints(resultRelInfo, slot, estate, mtstate);
  
  		/*
  		 * Also check the tuple against the partition constraint, if there is
  		 * one; except that if we got here via tuple-routing, we don't need to
  		 * if there's no BR trigger defined on the partition.
  		 */
  		if (resultRelInfo->ri_PartitionCheck &&
  				(resultRelInfo->ri_PartitionRoot == NULL ||
  				 (resultRelInfo->ri_TrigDesc &&
  					resultRelInfo->ri_TrigDesc->trig_insert_before_row)))
  			ExecPartitionCheck(resultRelInfo, slot, estate, true);
  
  		if (onconflict != ONCONFLICT_NONE && resultRelInfo->ri_NumIndices > 0)
  		{
  			/* Perform a speculative insertion. */
  			uint32		specToken;
  			ItemPointerData conflictTid;
  			bool		specConflict;
  			List	   *arbiterIndexes;
  
  			arbiterIndexes = resultRelInfo->ri_onConflictArbiterIndexes;
  
  			/*
  			 * Do a non-conclusive check for conflicts first.
  			 *
  			 * We're not holding any locks yet, so this doesn't guarantee that
  			 * the later insert won't conflict.  But it avoids leaving behind
  			 * a lot of canceled speculative insertions, if you run a lot of
  			 * INSERT ON CONFLICT statements that do conflict.
  			 *
  			 * We loop back here if we find a conflict below, either during
  			 * the pre-check, or when we re-check after inserting the tuple
  			 * speculatively.
  			 */
  	vlock:
  			specConflict = false;
  			if (!ExecCheckIndexConstraints(slot, estate, &conflictTid,
  										   arbiterIndexes))
  			{
  				/* committed conflict tuple found */
  				if (onconflict == ONCONFLICT_UPDATE)
  				{
  					/*
  					 * In case of ON CONFLICT DO UPDATE, execute the UPDATE
  					 * part.  Be prepared to retry if the UPDATE fails because
  					 * of another concurrent UPDATE/DELETE to the conflict
  					 * tuple.
  					 */
  					TupleTableSlot *returning = NULL;
  
  					if (ExecOnConflictUpdate(mtstate, resultRelInfo,
  											 &conflictTid, planSlot, slot,
  											 estate, canSetTag, &returning))
  					{
  						InstrCountTuples2(&mtstate->ps, 1);
  						result = returning;
  						goto conflict_resolved;
  					}
  					else
  						goto vlock;
  				}
  				else
  				{
  					/*
  					 * In case of ON CONFLICT DO NOTHING, do nothing. However,
  					 * verify that the tuple is visible to the executor's MVCC
  					 * snapshot at higher isolation levels.
  					 */
  					Assert(onconflict == ONCONFLICT_NOTHING);
  					if (!IsYBRelation(resultRelationDesc)) {
  						// YugaByte does not use Postgres transaction control code.
  						ExecCheckTIDVisible(estate, resultRelInfo, &conflictTid);
  					}
  					InstrCountTuples2(&mtstate->ps, 1);
  					result = NULL;
  					goto conflict_resolved;
  				}
  			}
  
  			if (IsYBRelation(resultRelationDesc))
  			{
  				/*
  				 * YugaByte handles transaction-control internally, so speculative token are not being
  				 * locked and released in this call.
  				 * TODO(Mikhail) Verify the YugaByte transaction support works properly for on-conflict.
  				 */
  				newId = YBCHeapInsert(slot, tuple, estate);
  
  				/* insert index entries for tuple */
  				recheckIndexes = ExecInsertIndexTuples(slot, tuple,
  													   estate, true, &specConflict,
  													   arbiterIndexes);
  			}
  			else
  			{
  				/*
  				 * Before we start insertion proper, acquire our "speculative
  				 * insertion lock".  Others can use that to wait for us to decide
  				 * if we're going to go ahead with the insertion, instead of
  				 * waiting for the whole transaction to complete.
  				 */
  				specToken = SpeculativeInsertionLockAcquire(GetCurrentTransactionId());
  				HeapTupleHeaderSetSpeculativeToken(tuple->t_data, specToken);
  
  				/* insert the tuple, with the speculative token */
  				newId = heap_insert(resultRelationDesc, tuple,
  									estate->es_output_cid,
  									HEAP_INSERT_SPECULATIVE,
  									NULL);
  
  				/* insert index entries for tuple */
  				recheckIndexes = ExecInsertIndexTuples(slot, tuple,
  													   estate, true, &specConflict,
  													   arbiterIndexes);
  
  				/* adjust the tuple's state accordingly */
  				if (!specConflict)
  					heap_finish_speculative(resultRelationDesc, tuple);
  				else
  					heap_abort_speculative(resultRelationDesc, tuple);
  
  				/*
  				 * Wake up anyone waiting for our decision.  They will re-check
  				 * the tuple, see that it's no longer speculative, and wait on our
  				 * XID as if this was a regularly inserted tuple all along.  Or if
  				 * we killed the tuple, they will see it's dead, and proceed as if
  				 * the tuple never existed.
  				 */
  				SpeculativeInsertionLockRelease(GetCurrentTransactionId());
  
  				/*
  				 * If there was a conflict, start from the beginning.  We'll do
  				 * the pre-check again, which will now find the conflicting tuple
  				 * (unless it aborts before we get there).
  				 */
  				if (specConflict)
  				{
  					list_free(recheckIndexes);
  					goto vlock;
  				}
  			}
  
  			/* Since there was no more insertion conflict, we're done with ON CONFLICT DO UPDATE */
  		}
  		else
  		{
  			/*
  			 * insert the tuple normally.
  			 *
  			 * Note: heap_insert returns the tid (location) of the new tuple
  			 * in the t_self field.
  			 */
  			if (IsYBRelation(resultRelationDesc))
  			{
  				newId = YBCHeapInsert(slot, tuple, estate);
  
  				/* insert index entries for tuple */
  				if (YBCRelInfoHasSecondaryIndices(resultRelInfo))
  					recheckIndexes = ExecInsertIndexTuples(slot, tuple, estate, false, NULL, NIL);
  			}
  			else
  			{
  				newId = heap_insert(resultRelationDesc, tuple,
  									estate->es_output_cid,
  									0, NULL);
  
  				/* insert index entries for tuple */
  				if (resultRelInfo->ri_NumIndices > 0)
  					recheckIndexes = ExecInsertIndexTuples(slot, tuple,
  					                                       estate, false, NULL,
  					                                       NIL);
  			}
  		}
  	}
  
  	if (canSetTag)
  	{
  		(estate->es_processed)++;
  		estate->es_lastoid = newId;
  		setLastTid(&(tuple->t_self));
  	}
  
  	/*
  	 * If this insert is the result of a partition key update that moved the
  	 * tuple to a new partition, put this row into the transition NEW TABLE,
  	 * if there is one. We need to do this separately for DELETE and INSERT
  	 * because they happen on different tables.
  	 */
  	ar_insert_trig_tcs = mtstate->mt_transition_capture;
  	if (mtstate->operation == CMD_UPDATE && mtstate->mt_transition_capture
  		&& mtstate->mt_transition_capture->tcs_update_new_table)
  	{
  		ExecARUpdateTriggers(estate, resultRelInfo, NULL,
  							 NULL,
  							 tuple,
  							 NULL,
  							 mtstate->mt_transition_capture);
  
  		/*
  		 * We've already captured the NEW TABLE row, so make sure any AR
  		 * INSERT trigger fired below doesn't capture it again.
  		 */
  		ar_insert_trig_tcs = NULL;
  	}
  
  	/* AFTER ROW INSERT Triggers */
  	ExecARInsertTriggers(estate, resultRelInfo, tuple, recheckIndexes,
  						 ar_insert_trig_tcs);
  
  	list_free(recheckIndexes);
  
  	/*
  	 * Check any WITH CHECK OPTION constraints from parent views.  We are
  	 * required to do this after testing all constraints and uniqueness
  	 * violations per the SQL spec, so we do it after actually inserting the
  	 * record into the heap and all indexes.
  	 *
  	 * ExecWithCheckOptions will elog(ERROR) if a violation is found, so the
  	 * tuple will never be seen, if it violates the WITH CHECK OPTION.
  	 *
  	 * ExecWithCheckOptions() will skip any WCOs which are not of the kind we
  	 * are looking for at this point.
  	 */
  	if (resultRelInfo->ri_WithCheckOptions != NIL)
  		ExecWithCheckOptions(WCO_VIEW_CHECK, resultRelInfo, slot, estate);
  
  	/* Process RETURNING if present */
    if (resultRelInfo->ri_projectReturning)
  		result = ExecProcessReturning(resultRelInfo, slot, planSlot);
  
  conflict_resolved:
  	if (estate->yb_conflict_slot != NULL) {
  		ExecDropSingleTupleTableSlot(estate->yb_conflict_slot);
  		estate->yb_conflict_slot = NULL;
  	}
  	return result;
  }
  
  /* ----------------------------------------------------------------
   *		ExecDelete
   *
   *		DELETE is like UPDATE, except that we delete the tuple and no
   *		index modifications are needed.
   *
   *		When deleting from a table, tupleid identifies the tuple to
   *		delete and oldtuple is NULL.  When deleting from a view,
   *		oldtuple is passed to the INSTEAD OF triggers and identifies
   *		what to delete, and tupleid is invalid.  When deleting from a
   *		foreign table, tupleid is invalid; the FDW has to figure out
   *		which row to delete using data from the planSlot.  oldtuple is
   *		passed to foreign table triggers; it is NULL when the foreign
   *		table has no relevant triggers.  We use tupleDeleted to indicate
   *		whether the tuple is actually deleted, callers can use it to
   *		decide whether to continue the operation.  When this DELETE is a
   *		part of an UPDATE of partition-key, then the slot returned by
   *		EvalPlanQual() is passed back using output parameter epqslot.
   *
   *		Returns RETURNING result if any, otherwise NULL.
   * ----------------------------------------------------------------
   */
  static TupleTableSlot *
  ExecDelete(ModifyTableState *mtstate,
  		   ItemPointer tupleid,
  		   HeapTuple oldtuple,
  		   TupleTableSlot *planSlot,
  		   EPQState *epqstate,
  		   EState *estate,
  		   bool processReturning,
  		   bool canSetTag,
  		   bool changingPart,
  		   bool *tupleDeleted,
  		   TupleTableSlot **epqslot)
  {
  	ResultRelInfo *resultRelInfo;
  	Relation	resultRelationDesc;
  	HTSU_Result result;
  	HeapUpdateFailureData hufd;
  	TupleTableSlot *slot = NULL;
  	TransitionCaptureState *ar_delete_trig_tcs;
  
  	if (tupleDeleted)
  		*tupleDeleted = false;
  
  	/*
  	 * get information on the (current) result relation
  	 */
  	resultRelInfo = estate->es_result_relation_info;
  	resultRelationDesc = resultRelInfo->ri_RelationDesc;
  
  	/* BEFORE ROW DELETE Triggers */
  	if (resultRelInfo->ri_TrigDesc &&
  		resultRelInfo->ri_TrigDesc->trig_delete_before_row)
  	{
  		bool		dodelete;
  
  		dodelete = ExecBRDeleteTriggers(estate, epqstate, resultRelInfo,
  										tupleid, oldtuple, epqslot);
  
  		if (!dodelete)			/* "do nothing" */
  			return NULL;
  	}
  
  	/* INSTEAD OF ROW DELETE Triggers */
  	if (resultRelInfo->ri_TrigDesc &&
  		resultRelInfo->ri_TrigDesc->trig_delete_instead_row)
  	{
  		bool		dodelete;
  
  		Assert(oldtuple != NULL);
  		dodelete = ExecIRDeleteTriggers(estate, resultRelInfo, oldtuple);
  
  		if (!dodelete)			/* "do nothing" */
  			return NULL;
  	}
  	else if (resultRelInfo->ri_FdwRoutine)
  	{
  		HeapTuple	tuple;
  
  		/*
  		 * delete from foreign table: let the FDW do it
  		 *
  		 * We offer the trigger tuple slot as a place to store RETURNING data,
  		 * although the FDW can return some other slot if it wants.  Set up
  		 * the slot's tupdesc so the FDW doesn't need to do that for itself.
  		 */
  		slot = estate->es_trig_tuple_slot;
  		if (slot->tts_tupleDescriptor != RelationGetDescr(resultRelationDesc))
  			ExecSetSlotDescriptor(slot, RelationGetDescr(resultRelationDesc));
  
  		slot = resultRelInfo->ri_FdwRoutine->ExecForeignDelete(estate,
  															   resultRelInfo,
  															   slot,
  															   planSlot);
  
  		if (slot == NULL)		/* "do nothing" */
  			return NULL;
  
  		/*
  		 * RETURNING expressions might reference the tableoid column, so
  		 * initialize t_tableOid before evaluating them.
  		 */
  		if (slot->tts_isempty)
  			ExecStoreAllNullTuple(slot);
  		tuple = ExecMaterializeSlot(slot);
  		tuple->t_tableOid = RelationGetRelid(resultRelationDesc);
  	}
  	else if (IsYBRelation(resultRelationDesc))
  	{
  		bool row_found = YBCExecuteDelete(resultRelationDesc, planSlot, estate,
  										  mtstate, changingPart);
  		if (!row_found)
  		{
  			/*
  			 * No row was found. This is possible if it's a single row txn
  			 * and there is no row to delete (since we do not first do a scan).
  			 */
  			return NULL;
  		}
  
  		if (YBCRelInfoHasSecondaryIndices(resultRelInfo))
  		{
  			Datum	ybctid = YBCGetYBTupleIdFromSlot(planSlot);
  
  			/* Delete index entries of the old tuple */
  			ExecDeleteIndexTuples(ybctid, oldtuple, estate);
  		}
  	}
  	else
  	{
  		/*
  		 * delete the tuple
  		 *
  		 * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check
  		 * that the row to be deleted is visible to that snapshot, and throw a
  		 * can't-serialize error if not. This is a special-case behavior
  		 * needed for referential integrity updates in transaction-snapshot
  		 * mode transactions.
  		 */
  ldelete:;
  		result = heap_delete(resultRelationDesc, tupleid,
  							 estate->es_output_cid,
  							 estate->es_crosscheck_snapshot,
  							 true /* wait for commit */ ,
  							 &hufd,
  							 changingPart);
  		switch (result)
  		{
  			case HeapTupleSelfUpdated:
  
  				/*
  				 * The target tuple was already updated or deleted by the
  				 * current command, or by a later command in the current
  				 * transaction.  The former case is possible in a join DELETE
  				 * where multiple tuples join to the same target tuple. This
  				 * is somewhat questionable, but Postgres has always allowed
  				 * it: we just ignore additional deletion attempts.
  				 *
  				 * The latter case arises if the tuple is modified by a
  				 * command in a BEFORE trigger, or perhaps by a command in a
  				 * volatile function used in the query.  In such situations we
  				 * should not ignore the deletion, but it is equally unsafe to
  				 * proceed.  We don't want to discard the original DELETE
  				 * while keeping the triggered actions based on its deletion;
  				 * and it would be no better to allow the original DELETE
  				 * while discarding updates that it triggered.  The row update
  				 * carries some information that might be important according
  				 * to business rules; so throwing an error is the only safe
  				 * course.
  				 *
  				 * If a trigger actually intends this type of interaction, it
  				 * can re-execute the DELETE and then return NULL to cancel
  				 * the outer delete.
  				 */
  				if (hufd.cmax != estate->es_output_cid)
  					ereport(ERROR,
  							(errcode(ERRCODE_TRIGGERED_DATA_CHANGE_VIOLATION),
  							 errmsg("tuple to be updated was already modified by an operation triggered by the current command"),
  							 errhint("Consider using an AFTER trigger instead of a BEFORE trigger to propagate changes to other rows.")));
  
  				/* Else, already deleted by self; nothing to do */
  				return NULL;
  
  			case HeapTupleMayBeUpdated:
  				break;
  
  			case HeapTupleUpdated:
  				if (IsolationUsesXactSnapshot())
  					ereport(ERROR,
  							(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
  							 errmsg("could not serialize access due to concurrent update")));
  				if (ItemPointerIndicatesMovedPartitions(&hufd.ctid))
  					ereport(ERROR,
  							(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
  							 errmsg("tuple to be deleted was already moved to another partition due to concurrent update")));
  
  				if (!ItemPointerEquals(tupleid, &hufd.ctid))
  				{
  					TupleTableSlot *my_epqslot;
  
  					my_epqslot = EvalPlanQual(estate,
  											  epqstate,
  											  resultRelationDesc,
  											  resultRelInfo->ri_RangeTableIndex,
  											  LockTupleExclusive,
  											  &hufd.ctid,
  											  hufd.xmax);
  					if (!TupIsNull(my_epqslot))
  					{
  						*tupleid = hufd.ctid;
  
  						/*
  						 * If requested, skip delete and pass back the updated
  						 * row.
  						 */
  						if (epqslot)
  						{
  							*epqslot = my_epqslot;
  							return NULL;
  						}
  						else
  							goto ldelete;
  					}
  				}
  				/* tuple already deleted; nothing to do */
  				return NULL;
  
  			default:
  				elog(ERROR, "unrecognized heap_delete status: %u", result);
  				return NULL;
  		}
  
  		/*
  		 * Note: Normally one would think that we have to delete index tuples
  		 * associated with the heap tuple now...
  		 *
  		 * ... but in POSTGRES, we have no need to do this because VACUUM will
  		 * take care of it later.  We can't delete index tuples immediately
  		 * anyway, since the tuple is still visible to other transactions.
  		 */
  	}
  
  	if (canSetTag)
  		(estate->es_processed)++;
  
  	/* Tell caller that the delete actually happened. */
  	if (tupleDeleted)
  		*tupleDeleted = true;
  
  	/*
  	 * If this delete is the result of a partition key update that moved the
  	 * tuple to a new partition, put this row into the transition OLD TABLE,
  	 * if there is one. We need to do this separately for DELETE and INSERT
  	 * because they happen on different tables.
  	 */
  	ar_delete_trig_tcs = mtstate->mt_transition_capture;
  	if (mtstate->operation == CMD_UPDATE && mtstate->mt_transition_capture
  		&& mtstate->mt_transition_capture->tcs_update_old_table)
  	{
  		ExecARUpdateTriggers(estate, resultRelInfo,
  							 tupleid,
  							 oldtuple,
  							 NULL,
  							 NULL,
  							 mtstate->mt_transition_capture);
  
  		/*
  		 * We've already captured the NEW TABLE row, so make sure any AR
  		 * DELETE trigger fired below doesn't capture it again.
  		 */
  		ar_delete_trig_tcs = NULL;
  	}
  
  	/* AFTER ROW DELETE Triggers */
  	ExecARDeleteTriggers(estate, resultRelInfo, tupleid, oldtuple,
  						 ar_delete_trig_tcs);
  
  	/* Process RETURNING if present and if requested */
  	if (processReturning && resultRelInfo->ri_projectReturning)
  	{
  		/*
  		 * We have to put the target tuple into a slot, which means first we
  		 * gotta fetch it.  We can use the trigger tuple slot.
  		 */
  		TupleTableSlot *rslot;
  		HeapTupleData deltuple;
  		Buffer		delbuffer;
  
  		if (resultRelInfo->ri_FdwRoutine)
  		{
  			/* FDW must have provided a slot containing the deleted row */
  			Assert(!TupIsNull(slot));
  			delbuffer = InvalidBuffer;
  		}
  		else if (IsYBRelation(resultRelationDesc))
  		{
  			if (mtstate->yb_mt_is_single_row_update_or_delete)
  			{
  				slot = planSlot;
  			}
  			else
  			{
  				slot = ExecFilterJunk(resultRelInfo->ri_junkFilter, planSlot);
  			}
  
  			delbuffer = InvalidBuffer;
  		}
  		else
  		{
  			slot = estate->es_trig_tuple_slot;
  			if (oldtuple != NULL)
  			{
  				deltuple = *oldtuple;
  				delbuffer = InvalidBuffer;
  			}
  			else
  			{
  				deltuple.t_self = *tupleid;
  				if (!heap_fetch(resultRelationDesc, SnapshotAny,
  								&deltuple, &delbuffer, false, NULL))
  					elog(ERROR, "failed to fetch deleted tuple for DELETE RETURNING");
  			}
  
  			if (slot->tts_tupleDescriptor != RelationGetDescr(resultRelationDesc))
  				ExecSetSlotDescriptor(slot, RelationGetDescr(resultRelationDesc));
  			ExecStoreHeapTuple(&deltuple, slot, false);
  		}
  
  		rslot = ExecProcessReturning(resultRelInfo, slot, planSlot);
  
  		/*
  		 * Before releasing the target tuple again, make sure rslot has a
  		 * local copy of any pass-by-reference values.
  		 */
  		ExecMaterializeSlot(rslot);
  
  		ExecClearTuple(slot);
  		if (BufferIsValid(delbuffer))
  			ReleaseBuffer(delbuffer);
  
  		return rslot;
  	}
  
  	return NULL;
  }
  
  /* ----------------------------------------------------------------
   * YBEqualDatums
   *
   * Function compares values of lhs and rhs datums with respect to value type and collation.
   *
   * Returns true in case value of lhs and rhs datums match.
   * ----------------------------------------------------------------
   */
  static bool
  YBEqualDatums(Datum lhs, Datum rhs, Oid atttypid, Oid collation)
  {
  	TypeCacheEntry *typentry = lookup_type_cache(atttypid, TYPECACHE_CMP_PROC_FINFO);
  	if (!OidIsValid(typentry->cmp_proc_finfo.fn_oid))
  		ereport(ERROR,
  		        (errcode(ERRCODE_UNDEFINED_FUNCTION),
  		         errmsg("could not identify a comparison function for type %s",
  		                format_type_be(typentry->type_id))));
  
  	FunctionCallInfoData locfcinfo;
  	InitFunctionCallInfoData(locfcinfo, &typentry->cmp_proc_finfo, 2, collation, NULL, NULL);
  	locfcinfo.arg[0] = lhs;
  	locfcinfo.arg[1] = rhs;
  	locfcinfo.argnull[0] = false;
  	locfcinfo.argnull[1] = false;
  	return DatumGetInt32(FunctionCallInvoke(&locfcinfo)) == 0;
  }
  
  /* ----------------------------------------------------------------
   * YBBuildExtraUpdatedCols
   *
   * Function compares attribute value in oldtuple and newtuple for attributes which are not in the
   * updatedCols set. Returns set of changed attributes or NULL.
   * ----------------------------------------------------------------
   */
  static Bitmapset*
  YBBuildExtraUpdatedCols(Relation rel,
                          HeapTuple oldtuple,
                          HeapTuple newtuple,
                          Bitmapset *updatedCols)
  {
  	if (bms_is_member(InvalidAttrNumber, updatedCols))
  		/* No extra work required in case the whore row is changed */
  		return NULL;
  
  	Bitmapset *result = NULL;
  	AttrNumber firstLowInvalidAttributeNumber = YBGetFirstLowInvalidAttributeNumber(rel);
  	TupleDesc tupleDesc = RelationGetDescr(rel);
  	for (int idx = 0; idx < tupleDesc->natts; ++idx)
  	{
  		FormData_pg_attribute *att_desc = TupleDescAttr(tupleDesc, idx);
  
  		AttrNumber attnum = att_desc->attnum;
  
  		/* Skip virtual (system) and dropped columns */
  		if (!IsRealYBColumn(rel, attnum))
  			continue;
  
  		int bms_idx = attnum - firstLowInvalidAttributeNumber;
  		if (bms_is_member(bms_idx, updatedCols))
  			continue;
  
  		bool old_is_null = false;
  		bool new_is_null = false;
  		Datum old_value = heap_getattr(oldtuple, attnum, tupleDesc, &old_is_null);
  		Datum new_value = heap_getattr(newtuple, attnum, tupleDesc, &new_is_null);
  		if (old_is_null != new_is_null ||
  		    (!new_is_null && !YBEqualDatums(old_value,
  		                                    new_value,
  		                                    att_desc->atttypid,
  		                                    att_desc->attcollation)))
  		{
  			result = bms_add_member(result, bms_idx);
  		}
  	}
  	return result;
  }
  
  
  /*
   * ExecCrossPartitionUpdate --- Move an updated tuple to another partition.
   *
   * This works by first deleting the old tuple from the current partition,
   * followed by inserting the new tuple into the root parent table, that is,
   * mtstate->rootResultRelInfo.  It will be re-routed from there to the
   * correct partition.
   *
   * Returns true if the tuple has been successfully moved, or if it's found
   * that the tuple was concurrently deleted so there's nothing more to do
   * for the caller.
   *
   * False is returned if the tuple we're trying to move is found to have been
   * concurrently updated.  In that case, the caller must to check if the
   * updated tuple that's returned in *retry_slot still needs to be re-routed,
   * and call this function again or perform a regular update accordingly.
   */
  static bool
  ExecCrossPartitionUpdate(ModifyTableState *mtstate,
  						 ResultRelInfo *resultRelInfo,
  						 ItemPointer tupleid, HeapTuple oldtuple,
  						 TupleTableSlot *slot, TupleTableSlot *planSlot,
  						 EPQState *epqstate, bool canSetTag,
  						 TupleTableSlot **retry_slot,
  						 TupleTableSlot **inserted_tuple)
  {
  	EState	   *estate = mtstate->ps.state;
  	PartitionTupleRouting *proute = mtstate->mt_partition_tuple_routing;
  	int			map_index;
  	TupleConversionMap *tupconv_map;
  	TupleConversionMap *saved_tcs_map = NULL;
  	bool		tuple_deleted;
  	TupleTableSlot *epqslot = NULL;
  	bool    prev_yb_is_single_row_modify_txn =
  		estate->es_yb_is_single_row_modify_txn;
  
  	*inserted_tuple = NULL;
  	*retry_slot = NULL;
  
  	/*
  	 * Disallow an INSERT ON CONFLICT DO UPDATE that causes the original row
  	 * to migrate to a different partition.  Maybe this can be implemented
  	 * some day, but it seems a fringe feature with little redeeming value.
  	 */
  	if (((ModifyTable *) mtstate->ps.plan)->onConflictAction == ONCONFLICT_UPDATE)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("invalid ON UPDATE specification"),
  				 errdetail("The result tuple would appear in a different partition than the original tuple.")));
  
  	/*
  	 * When an UPDATE is run on a leaf partition, we will not have partition
  	 * tuple routing set up.  In that case, fail with partition constraint
  	 * violation error.
  	 */
  	if (proute == NULL)
  		ExecPartitionCheckEmitError(resultRelInfo, slot, estate);
  
  	/*
  	 * Row movement, part 1.  Delete the tuple, but skip RETURNING processing.
  	 * We want to return rows from INSERT.
  	 */
  	ExecDelete(mtstate, tupleid, oldtuple, planSlot,
  			   epqstate, estate,
  			   false,			/* processReturning */
  			   false,			/* canSetTag */
  			   true,			/* changingPart */
  			   &tuple_deleted, &epqslot);
  
  	/*
  	 * For some reason if DELETE didn't happen (e.g. trigger prevented it, or
  	 * it was already deleted by self, or it was concurrently deleted by
  	 * another transaction), then we should skip the insert as well;
  	 * otherwise, an UPDATE could cause an increase in the total number of
  	 * rows across all partitions, which is clearly wrong.
  	 *
  	 * For a normal UPDATE, the case where the tuple has been the subject of a
  	 * concurrent UPDATE or DELETE would be handled by the EvalPlanQual
  	 * machinery, but for an UPDATE that we've translated into a DELETE from
  	 * this partition and an INSERT into some other partition, that's not
  	 * available, because CTID chains can't span relation boundaries.  We
  	 * mimic the semantics to a limited extent by skipping the INSERT if the
  	 * DELETE fails to find a tuple.  This ensures that two concurrent
  	 * attempts to UPDATE the same tuple at the same time can't turn one tuple
  	 * into two, and that an UPDATE of a just-deleted tuple can't resurrect
  	 * it.
  	 */
  	if (!tuple_deleted)
  	{
  		/*
  		 * epqslot will be typically NULL.  But when ExecDelete() finds that
  		 * another transaction has concurrently updated the same row, it
  		 * re-fetches the row, skips the delete, and epqslot is set to the
  		 * re-fetched tuple slot.  In that case, we need to do all the checks
  		 * again.
  		 */
  		if (TupIsNull(epqslot))
  			return true;
  		else
  		{
  			*retry_slot = ExecFilterJunk(resultRelInfo->ri_junkFilter, epqslot);
  			return false;
  		}
  	}
  
  	/*
  	 * resultRelInfo is one of the per-subplan resultRelInfos.  So we should
  	 * convert the tuple into root's tuple descriptor, since ExecInsert()
  	 * starts the search from root.  The tuple conversion map list is in the
  	 * order of mtstate->resultRelInfo[], so to retrieve the one for this
  	 * resultRel, we need to know the position of the resultRel in
  	 * mtstate->resultRelInfo[].
  	 */
  	map_index = resultRelInfo - mtstate->resultRelInfo;
  	Assert(map_index >= 0 && map_index < mtstate->mt_nplans);
  	tupconv_map = tupconv_map_for_subplan(mtstate, map_index);
  	if (tupconv_map != NULL)
  		slot = execute_attr_map_slot(tupconv_map->attrMap,
  									 slot,
  									 proute->root_tuple_slot);
  
  	/*
  	 * ExecInsert() may scribble on mtstate->mt_transition_capture, so save
  	 * the currently active map.
   	*/
  	if (mtstate->mt_transition_capture)
   		saved_tcs_map = mtstate->mt_transition_capture->tcs_map;
  
  	/*
  	 * Prepare for tuple routing, making it look like we're inserting
  	 * into the root.
  	 */
  	Assert(mtstate->rootResultRelInfo != NULL);
  	slot = ExecPrepareTupleRouting(mtstate, estate, proute,
  								   mtstate->rootResultRelInfo, slot);
  
  	*inserted_tuple = ExecInsert(mtstate, slot, planSlot, estate, canSetTag);
  
  	/* Revert ExecPrepareTupleRouting's node change. */
  	estate->es_result_relation_info = resultRelInfo;
  	estate->es_yb_is_single_row_modify_txn = prev_yb_is_single_row_modify_txn;
  	if (mtstate->mt_transition_capture)
  	{
  		mtstate->mt_transition_capture->tcs_original_insert_tuple = NULL;
  		mtstate->mt_transition_capture->tcs_map = saved_tcs_map;
  	}
  
  	/* We're done moving. */
  	return true;
  }
  
  /* ----------------------------------------------------------------
   *		ExecUpdate
   *
   *		note: we can't run UPDATE queries with transactions
   *		off because UPDATEs are actually INSERTs and our
   *		scan will mistakenly loop forever, updating the tuple
   *		it just inserted..  This should be fixed but until it
   *		is, we don't want to get stuck in an infinite loop
   *		which corrupts your database..
   *
   *		When updating a table, tupleid identifies the tuple to
   *		update and oldtuple is NULL.  When updating a view, oldtuple
   *		is passed to the INSTEAD OF triggers and identifies what to
   *		update, and tupleid is invalid.  When updating a foreign table,
   *		tupleid is invalid; the FDW has to figure out which row to
   *		update using data from the planSlot.  oldtuple is passed to
   *		foreign table triggers; it is NULL when the foreign table has
   *		no relevant triggers.
   *
   *		Returns RETURNING result if any, otherwise NULL.
   * ----------------------------------------------------------------
   */
  static TupleTableSlot *
  ExecUpdate(ModifyTableState *mtstate,
  		   ItemPointer tupleid,
  		   HeapTuple oldtuple,
  		   TupleTableSlot *slot,
  		   TupleTableSlot *planSlot,
  		   EPQState *epqstate,
  		   EState *estate,
  		   bool canSetTag)
  {
  	HeapTuple	tuple;
  	ResultRelInfo *resultRelInfo;
  	Relation	resultRelationDesc;
  	HTSU_Result result;
  	HeapUpdateFailureData hufd;
  	List	   *recheckIndexes = NIL;
  
  	/*
  	 * abort the operation if not running transactions
  	 */
  	if (IsBootstrapProcessingMode())
  		elog(ERROR, "cannot UPDATE during bootstrap");
  
  	/*
  	 * get the heap tuple out of the tuple table slot, making sure we have a
  	 * writable copy
  	 */
  	tuple = ExecMaterializeSlot(slot);
  
  	/*
  	 * get information on the (current) result relation
  	 */
  	resultRelInfo = estate->es_result_relation_info;
  	resultRelationDesc = resultRelInfo->ri_RelationDesc;
  
  	bool beforeRowUpdateTriggerFired = false;
  
  	/* BEFORE ROW UPDATE Triggers */
  	if (resultRelInfo->ri_TrigDesc &&
  		resultRelInfo->ri_TrigDesc->trig_update_before_row)
  	{
  		slot = ExecBRUpdateTriggers(estate, epqstate, resultRelInfo,
  									tupleid, oldtuple, slot);
  
  		if (slot == NULL)		/* "do nothing" */
  			return NULL;
  
  		/* trigger might have changed tuple */
  		tuple = ExecMaterializeSlot(slot);
  		beforeRowUpdateTriggerFired = true;
  	}
  
  	/* INSTEAD OF ROW UPDATE Triggers */
  	if (resultRelInfo->ri_TrigDesc &&
  		resultRelInfo->ri_TrigDesc->trig_update_instead_row)
  	{
  		slot = ExecIRUpdateTriggers(estate, resultRelInfo,
  									oldtuple, slot);
  
  		if (slot == NULL)		/* "do nothing" */
  			return NULL;
  
  		/* trigger might have changed tuple */
  		tuple = ExecMaterializeSlot(slot);
  	}
  	else if (resultRelInfo->ri_FdwRoutine)
  	{
  		/*
  		 * update in foreign table: let the FDW do it
  		 */
  		slot = resultRelInfo->ri_FdwRoutine->ExecForeignUpdate(estate,
  															   resultRelInfo,
  															   slot,
  															   planSlot);
  
  		if (slot == NULL)		/* "do nothing" */
  			return NULL;
  
  		/* FDW might have changed tuple */
  		tuple = ExecMaterializeSlot(slot);
  
  		/*
  		 * AFTER ROW Triggers or RETURNING expressions might reference the
  		 * tableoid column, so initialize t_tableOid before evaluating them.
  		 */
  		tuple->t_tableOid = RelationGetRelid(resultRelationDesc);
  	}
  	else if (IsYBRelation(resultRelationDesc))
  	{
  		bool		partition_constraint_failed;
  
  		yb_lreplace:;
  		/*
  		 * Check the constraints of the tuple.
  		 */
  		if (resultRelationDesc->rd_att->constr)
  			ExecConstraints(resultRelInfo, slot, estate, mtstate);
  
  		/*
  		 * Verify that the update does not violate partition constraints.
  		 */
  		partition_constraint_failed =
  			resultRelInfo->ri_PartitionCheck &&
  			!ExecPartitionCheck(resultRelInfo, slot, estate, false /* emitError */);
  
  		if (!partition_constraint_failed && resultRelInfo->ri_WithCheckOptions != NIL)
  		{
  			/*
  			 * ExecWithCheckOptions() will skip any WCOs which are not of the
  			 * kind we are looking for at this point.
  			 */
  			ExecWithCheckOptions(WCO_RLS_UPDATE_CHECK, resultRelInfo, slot, estate);
  		}
  
  
  		/*
  		 * If a partition check failed, try to move the row into the right
  		 * partition.
  		 */
  		if (partition_constraint_failed)
  		{
  			TupleTableSlot *inserted_tuple, *retry_slot;
  			bool            retry;
  
  
  			/*
  			 * ExecCrossPartitionUpdate will first DELETE the row from the
  			 * partition it's currently in and then insert it back into the
  			 * root table, which will re-route it to the correct partition.
  			 * The first part may have to be repeated if it is detected that
  			 * the tuple we're trying to move has been concurrently updated.
   			 */
  
  			retry = !ExecCrossPartitionUpdate(mtstate, resultRelInfo, tupleid,
  											  oldtuple, slot, planSlot,
  											  epqstate, canSetTag,
  											  &retry_slot, &inserted_tuple);
  			if (retry)
  			{
  				slot = retry_slot;
  				tuple = ExecMaterializeSlot(slot);
  				goto yb_lreplace;
   			}
  
  			return inserted_tuple;
   		}
  
  		RangeTblEntry *rte = rt_fetch(resultRelInfo->ri_RangeTableIndex,
  									  estate->es_range_table);
  
  		bool row_found = false;
  
  		Bitmapset *actualUpdatedCols = rte->updatedCols;
  		Bitmapset *extraUpdatedCols = NULL;
  		if (beforeRowUpdateTriggerFired)
  		{
  			/* trigger might have changed tuple */
  			extraUpdatedCols = YBBuildExtraUpdatedCols(
  				resultRelationDesc, oldtuple, tuple, rte->updatedCols);
  			if (extraUpdatedCols)
  			{
  				extraUpdatedCols = bms_add_members(extraUpdatedCols, rte->updatedCols);
  				actualUpdatedCols = extraUpdatedCols;
  			}
  		}
  		bool is_pk_updated =
  			bms_overlap(YBGetTablePrimaryKeyBms(resultRelationDesc), actualUpdatedCols);
  
  		if (is_pk_updated)
  		{
  			YBCExecuteUpdateReplace(resultRelationDesc, planSlot, tuple, estate, mtstate);
  			row_found = true;
  		}
  		else
  		{
  			row_found = YBCExecuteUpdate(
  				resultRelationDesc, planSlot, tuple, estate, mtstate, actualUpdatedCols);
  		}
  
  		bms_free(extraUpdatedCols);
  		if (!row_found)
  		{
  			/*
  			 * No row was found. This is possible if it's a single row txn
  			 * and there is no row to update (since we do not first do a scan).
  			 */
  			return NULL;
  		}
  
  		/* Update indices selectively if necessary, Single row updates do not affect indices */
  		if (YBCRelInfoHasSecondaryIndices(resultRelInfo) &&
  		    !mtstate->yb_mt_is_single_row_update_or_delete)
  		{
  			Datum	ybctid = YBCGetYBTupleIdFromSlot(planSlot);
  			List *no_update_index_list = ((ModifyTable *)mtstate->ps.plan)->no_update_index_list;
  
  			/* Delete index entries of the old tuple */
  			ExecDeleteIndexTuplesOptimized(ybctid, oldtuple, estate, no_update_index_list);
  
  			/* Insert new index entries for tuple */
  			recheckIndexes = ExecInsertIndexTuplesOptimized(
  			    slot, tuple, estate, false, NULL, NIL, no_update_index_list);
  		}
  	}
  	else
  	{
  		LockTupleMode lockmode;
  		bool		partition_constraint_failed;
  
  		/*
  		 * Constraints might reference the tableoid column, so initialize
  		 * t_tableOid before evaluating them.
  		 */
  		tuple->t_tableOid = RelationGetRelid(resultRelationDesc);
  
  		/*
  		 * Check any RLS UPDATE WITH CHECK policies
  		 *
  		 * If we generate a new candidate tuple after EvalPlanQual testing, we
  		 * must loop back here and recheck any RLS policies and constraints.
  		 * (We don't need to redo triggers, however.  If there are any BEFORE
  		 * triggers then trigger.c will have done heap_lock_tuple to lock the
  		 * correct tuple, so there's no need to do them again.)
  		 */
  lreplace:;
  
  		/*
  		 * If partition constraint fails, this row might get moved to another
  		 * partition, in which case we should check the RLS CHECK policy just
  		 * before inserting into the new partition, rather than doing it here.
  		 * This is because a trigger on that partition might again change the
  		 * row.  So skip the WCO checks if the partition constraint fails.
  		 */
  		partition_constraint_failed =
  			resultRelInfo->ri_PartitionCheck &&
  			!ExecPartitionCheck(resultRelInfo, slot, estate, false);
  
  		if (!partition_constraint_failed &&
  			resultRelInfo->ri_WithCheckOptions != NIL)
  		{
  			/*
  			 * ExecWithCheckOptions() will skip any WCOs which are not of the
  			 * kind we are looking for at this point.
  			 */
  			ExecWithCheckOptions(WCO_RLS_UPDATE_CHECK,
  								 resultRelInfo, slot, estate);
  		}
  
  		/*
  		 * If a partition check failed, try to move the row into the right
  		 * partition.
  		 */
  		if (partition_constraint_failed)
  		{
  			TupleTableSlot *inserted_tuple, *retry_slot;
  			bool            retry;
  
  
  			/*
  			 * ExecCrossPartitionUpdate will first DELETE the row from the
  			 * partition it's currently in and then insert it back into the
  			 * root table, which will re-route it to the correct partition.
  			 * The first part may have to be repeated if it is detected that
  			 * the tuple we're trying to move has been concurrently updated.
   			 */
  
  			retry = !ExecCrossPartitionUpdate(mtstate, resultRelInfo, tupleid,
  											  oldtuple, slot, planSlot,
  											  epqstate, canSetTag,
  											  &retry_slot, &inserted_tuple);
  			if (retry)
  			{
  				slot = retry_slot;
  				tuple = ExecMaterializeSlot(slot);
  				goto lreplace;
   			}
  
  			return inserted_tuple;
   		}
  
  		/*
  		 * Check the constraints of the tuple.  We've already checked the
  		 * partition constraint above; however, we must still ensure the tuple
  		 * passes all other constraints, so we will call ExecConstraints() and
  		 * have it validate all remaining checks.
  		 */
  		if (resultRelationDesc->rd_att->constr)
  			ExecConstraints(resultRelInfo, slot, estate, mtstate);
  
  		/*
  		 * replace the heap tuple
  		 *
  		 * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check
  		 * that the row to be updated is visible to that snapshot, and throw a
  		 * can't-serialize error if not. This is a special-case behavior
  		 * needed for referential integrity updates in transaction-snapshot
  		 * mode transactions.
  		 */
  		result = heap_update(resultRelationDesc, tupleid, tuple,
  							 estate->es_output_cid,
  							 estate->es_crosscheck_snapshot,
  							 true /* wait for commit */ ,
  							 &hufd, &lockmode);
  		switch (result)
  		{
  			case HeapTupleSelfUpdated:
  
  				/*
  				 * The target tuple was already updated or deleted by the
  				 * current command, or by a later command in the current
  				 * transaction.  The former case is possible in a join UPDATE
  				 * where multiple tuples join to the same target tuple. This
  				 * is pretty questionable, but Postgres has always allowed it:
  				 * we just execute the first update action and ignore
  				 * additional update attempts.
  				 *
  				 * The latter case arises if the tuple is modified by a
  				 * command in a BEFORE trigger, or perhaps by a command in a
  				 * volatile function used in the query.  In such situations we
  				 * should not ignore the update, but it is equally unsafe to
  				 * proceed.  We don't want to discard the original UPDATE
  				 * while keeping the triggered actions based on it; and we
  				 * have no principled way to merge this update with the
  				 * previous ones.  So throwing an error is the only safe
  				 * course.
  				 *
  				 * If a trigger actually intends this type of interaction, it
  				 * can re-execute the UPDATE (assuming it can figure out how)
  				 * and then return NULL to cancel the outer update.
  				 */
  				if (hufd.cmax != estate->es_output_cid)
  					ereport(ERROR,
  							(errcode(ERRCODE_TRIGGERED_DATA_CHANGE_VIOLATION),
  							 errmsg("tuple to be updated was already modified by an operation triggered by the current command"),
  							 errhint("Consider using an AFTER trigger instead of a BEFORE trigger to propagate changes to other rows.")));
  
  				/* Else, already updated by self; nothing to do */
  				return NULL;
  
  			case HeapTupleMayBeUpdated:
  				break;
  
  			case HeapTupleUpdated:
  				if (IsolationUsesXactSnapshot())
  					ereport(ERROR,
  							(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
  							 errmsg("could not serialize access due to concurrent update")));
  				if (ItemPointerIndicatesMovedPartitions(&hufd.ctid))
  					ereport(ERROR,
  							(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
  							 errmsg("tuple to be updated was already moved to another partition due to concurrent update")));
  
  				if (!ItemPointerEquals(tupleid, &hufd.ctid))
  				{
  					TupleTableSlot *epqslot;
  
  					epqslot = EvalPlanQual(estate,
  										   epqstate,
  										   resultRelationDesc,
  										   resultRelInfo->ri_RangeTableIndex,
  										   lockmode,
  										   &hufd.ctid,
  										   hufd.xmax);
  					if (!TupIsNull(epqslot))
  					{
  						*tupleid = hufd.ctid;
  						slot = ExecFilterJunk(resultRelInfo->ri_junkFilter, epqslot);
  						tuple = ExecMaterializeSlot(slot);
  						goto lreplace;
  					}
  				}
  				/* tuple already deleted; nothing to do */
  				return NULL;
  
  			default:
  				elog(ERROR, "unrecognized heap_update status: %u", result);
  				return NULL;
  		}
  
  		/*
  		 * Note: instead of having to update the old index tuples associated
  		 * with the heap tuple, all we do is form and insert new index tuples.
  		 * This is because UPDATEs are actually DELETEs and INSERTs, and index
  		 * tuple deletion is done later by VACUUM (see notes in ExecDelete).
  		 * All we do here is insert new index tuples.  -cim 9/27/89
  		 */
  
  		/*
  		 * insert index entries for tuple
  		 *
  		 * Note: heap_update returns the tid (location) of the new tuple in
  		 * the t_self field.
  		 *
  		 * If it's a HOT update, we mustn't insert new index entries.
  		 */
  		if (resultRelInfo->ri_NumIndices > 0 && !HeapTupleIsHeapOnly(tuple))
  			recheckIndexes = ExecInsertIndexTuples(slot, tuple,
  												   estate, false, NULL, NIL);
  	}
  
  	if (canSetTag)
  		(estate->es_processed)++;
  
  	if (!((ModifyTable *)mtstate->ps.plan)->no_row_trigger)
  	{
  		/* AFTER ROW UPDATE Triggers */
  		ExecARUpdateTriggers(estate, resultRelInfo, tupleid, oldtuple, tuple,
  							recheckIndexes,
  							mtstate->operation == CMD_INSERT ?
  							mtstate->mt_oc_transition_capture :
  							mtstate->mt_transition_capture);
  	}
  	list_free(recheckIndexes);
  
  	/*
  	 * Check any WITH CHECK OPTION constraints from parent views.  We are
  	 * required to do this after testing all constraints and uniqueness
  	 * violations per the SQL spec, so we do it after actually updating the
  	 * record in the heap and all indexes.
  	 *
  	 * ExecWithCheckOptions() will skip any WCOs which are not of the kind we
  	 * are looking for at this point.
  	 */
  	if (resultRelInfo->ri_WithCheckOptions != NIL)
  		ExecWithCheckOptions(WCO_VIEW_CHECK, resultRelInfo, slot, estate);
  
  
  	/* Process RETURNING if present */
  	if (resultRelInfo->ri_projectReturning)
  	{
  		/*
  		 * Prepare the updated tuple in inner slot for RETURNING clause execution.
  		 * For ON CONFLICT DO UPDATE, the INSERT returning clause is setup
  		 * differently, so junkFilter is not needed.
  		 */
  		if (IsYBRelation(resultRelationDesc) && resultRelInfo->ri_junkFilter)
  			slot = ExecFilterJunk(resultRelInfo->ri_junkFilter, planSlot);
  
  		return ExecProcessReturning(resultRelInfo, slot, planSlot);
  	}
  
  	return NULL;
  }
  
  /*
   * ExecOnConflictUpdate --- execute UPDATE of INSERT ON CONFLICT DO UPDATE
   *
   * Try to lock tuple for update as part of speculative insertion.  If
   * a qual originating from ON CONFLICT DO UPDATE is satisfied, update
   * (but still lock row, even though it may not satisfy estate's
   * snapshot).
   *
   * Returns true if we're done (with or without an update), or false if
   * the caller must retry the INSERT from scratch.
   */
  static bool
  ExecOnConflictUpdate(ModifyTableState *mtstate,
  					 ResultRelInfo *resultRelInfo,
  					 ItemPointer conflictTid,
  					 TupleTableSlot *planSlot,
  					 TupleTableSlot *excludedSlot,
  					 EState *estate,
  					 bool canSetTag,
  					 TupleTableSlot **returning)
  {
  	ExprContext *econtext = mtstate->ps.ps_ExprContext;
  	Relation	relation = resultRelInfo->ri_RelationDesc;
  	ExprState  *onConflictSetWhere = resultRelInfo->ri_onConflict->oc_WhereClause;
  	HeapTupleData tuple;
  	HeapTuple	oldtuple = NULL;
  	HeapUpdateFailureData hufd;
  	LockTupleMode lockmode;
  	HTSU_Result test;
  	Buffer		buffer;
  
  	/*
  	 * This routine selects data and check with indexes for conflicts.
  	 * - When selecting data from disk, Postgres prepares a heap buffer to hold the selected row
  	 *   and performs transaction-control locking operations on the selected row.
  	 * - YugaByte usually uses Postgres heap buffer after selecting data from storage (DocDB).
  	 *   However, in this case, it's complicated to use the heap buffer because the two systems use
  	 *   different tuple IDs - "ybctid" vs "ctid".
  	 * - Also, YugaByte manages transactions separately from Postgres's plan execution.
  	 *
  	 * Coding-wise, Posgres writes tuple to heap buffer and writes its tuple ID to "conflictTid".
  	 * However, YugaByte writes the conflict tuple including its "ybctid" to execution state "estate"
  	 * and then frees the slot when done.
  	 */
  	if (IsYBBackedRelation(relation)) {
  		/* Not using heap buffer for YugaByte */
  		buffer = InvalidBuffer;
  
  		/* Ensure the heap tuple is initialized to invalid too. */
  		ItemPointerSetInvalid(&(tuple.t_self));
  		tuple.t_ybctid = (Datum) 0;
  
  		goto yb_skip_transaction_control_check;
  	}
  
  	/* Determine lock mode to use */
  	lockmode = ExecUpdateLockMode(estate, resultRelInfo);
  
  	/*
  	 * Lock tuple for update.  Don't follow updates when tuple cannot be
  	 * locked without doing so.  A row locking conflict here means our
  	 * previous conclusion that the tuple is conclusively committed is not
  	 * true anymore.
  	 */
  	tuple.t_self = *conflictTid;
  	test = heap_lock_tuple(relation, &tuple, estate->es_output_cid,
  						   lockmode, LockWaitBlock, false, &buffer,
  						   &hufd);
  	switch (test)
  	{
  		case HeapTupleMayBeUpdated:
  			/* success! */
  			break;
  
  		case HeapTupleInvisible:
  
  			/*
  			 * This can occur when a just inserted tuple is updated again in
  			 * the same command. E.g. because multiple rows with the same
  			 * conflicting key values are inserted.
  			 *
  			 * This is somewhat similar to the ExecUpdate()
  			 * HeapTupleSelfUpdated case.  We do not want to proceed because
  			 * it would lead to the same row being updated a second time in
  			 * some unspecified order, and in contrast to plain UPDATEs
  			 * there's no historical behavior to break.
  			 *
  			 * It is the user's responsibility to prevent this situation from
  			 * occurring.  These problems are why SQL-2003 similarly specifies
  			 * that for SQL MERGE, an exception must be raised in the event of
  			 * an attempt to update the same row twice.
  			 */
  			if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple.t_data)))
  				ereport(ERROR,
  						(errcode(ERRCODE_CARDINALITY_VIOLATION),
  						 errmsg("ON CONFLICT DO UPDATE command cannot affect row a second time"),
  						 errhint("Ensure that no rows proposed for insertion within the same command have duplicate constrained values.")));
  
  			/* This shouldn't happen */
  			elog(ERROR, "attempted to lock invisible tuple");
  			break;
  
  		case HeapTupleSelfUpdated:
  
  			/*
  			 * This state should never be reached. As a dirty snapshot is used
  			 * to find conflicting tuples, speculative insertion wouldn't have
  			 * seen this row to conflict with.
  			 */
  			elog(ERROR, "unexpected self-updated tuple");
  			break;
  
  		case HeapTupleUpdated:
  			if (IsolationUsesXactSnapshot())
  				ereport(ERROR,
  						(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
  						 errmsg("could not serialize access due to concurrent update")));
  
  			/*
  			 * As long as we don't support an UPDATE of INSERT ON CONFLICT for
  			 * a partitioned table we shouldn't reach to a case where tuple to
  			 * be lock is moved to another partition due to concurrent update
  			 * of the partition key.
  			 */
  			Assert(!ItemPointerIndicatesMovedPartitions(&hufd.ctid));
  
  			/*
  			 * Tell caller to try again from the very start.
  			 *
  			 * It does not make sense to use the usual EvalPlanQual() style
  			 * loop here, as the new version of the row might not conflict
  			 * anymore, or the conflicting tuple has actually been deleted.
  			 */
  			ReleaseBuffer(buffer);
  			return false;
  
  		default:
  			elog(ERROR, "unrecognized heap_lock_tuple status: %u", test);
  	}
  
  yb_skip_transaction_control_check:
  	/*
  	 * Success, the tuple is locked.
  	 *
  	 * Reset per-tuple memory context to free any expression evaluation
  	 * storage allocated in the previous cycle.
  	 */
  	ResetExprContext(econtext);
  
  	if (IsYugaByteEnabled())
  	{
  		oldtuple = ExecMaterializeSlot(estate->yb_conflict_slot);
  		ExecStoreBufferHeapTuple(oldtuple, mtstate->mt_existing, buffer);
  		planSlot->tts_tuple->t_ybctid = oldtuple->t_ybctid;
  	}
  	else
  	{
  		/*
  		 * Verify that the tuple is visible to our MVCC snapshot if the current
  		 * isolation level mandates that.
  		 *
  		 * It's not sufficient to rely on the check within ExecUpdate() as e.g.
  		 * CONFLICT ... WHERE clause may prevent us from reaching that.
  		 *
  		 * This means we only ever continue when a new command in the current
  		 * transaction could see the row, even though in READ COMMITTED mode the
  		 * tuple will not be visible according to the current statement's
  		 * snapshot.  This is in line with the way UPDATE deals with newer tuple
  		 * versions.
  		 */
  		ExecCheckHeapTupleVisible(estate, &tuple, buffer);
  
  		/* Store target's existing tuple in the state's dedicated slot */
  		ExecStoreBufferHeapTuple(&tuple, mtstate->mt_existing, buffer);
  	}
  
  	/*
  	 * Make tuple and any needed join variables available to ExecQual and
  	 * ExecProject.  The EXCLUDED tuple is installed in ecxt_innertuple, while
  	 * the target's existing tuple is installed in the scantuple.  EXCLUDED
  	 * has been made to reference INNER_VAR in setrefs.c, but there is no
  	 * other redirection.
  	 */
  	econtext->ecxt_scantuple = mtstate->mt_existing;
  	econtext->ecxt_innertuple = excludedSlot;
  	econtext->ecxt_outertuple = NULL;
  
  	if (!ExecQual(onConflictSetWhere, econtext))
  	{
  		/* YugaByte don't use the heap buffer to cache the conflict tuple */
  		if (!IsYugaByteEnabled())
  			ReleaseBuffer(buffer);
  		InstrCountFiltered1(&mtstate->ps, 1);
  		return true;			/* done with the tuple */
  	}
  
  	if (resultRelInfo->ri_WithCheckOptions != NIL)
  	{
  		/*
  		 * Check target's existing tuple against UPDATE-applicable USING
  		 * security barrier quals (if any), enforced here as RLS checks/WCOs.
  		 *
  		 * The rewriter creates UPDATE RLS checks/WCOs for UPDATE security
  		 * quals, and stores them as WCOs of "kind" WCO_RLS_CONFLICT_CHECK,
  		 * but that's almost the extent of its special handling for ON
  		 * CONFLICT DO UPDATE.
  		 *
  		 * The rewriter will also have associated UPDATE applicable straight
  		 * RLS checks/WCOs for the benefit of the ExecUpdate() call that
  		 * follows.  INSERTs and UPDATEs naturally have mutually exclusive WCO
  		 * kinds, so there is no danger of spurious over-enforcement in the
  		 * INSERT or UPDATE path.
  		 */
  		ExecWithCheckOptions(WCO_RLS_CONFLICT_CHECK, resultRelInfo,
  							 mtstate->mt_existing,
  							 mtstate->ps.state);
  	}
  
  	/* Project the new tuple version */
  	ExecProject(resultRelInfo->ri_onConflict->oc_ProjInfo);
  
  	/*
  	 * Note that it is possible that the target tuple has been modified in
  	 * this session, after the above heap_lock_tuple. We choose to not error
  	 * out in that case, in line with ExecUpdate's treatment of similar cases.
  	 * This can happen if an UPDATE is triggered from within ExecQual(),
  	 * ExecWithCheckOptions() or ExecProject() above, e.g. by selecting from a
  	 * wCTE in the ON CONFLICT's SET.
  	 */
  
  	/* Execute UPDATE with projection */
  	*returning = ExecUpdate(mtstate, &tuple.t_self, oldtuple,
  							mtstate->mt_conflproj, planSlot,
  							&mtstate->mt_epqstate, mtstate->ps.state,
  							canSetTag);
  
  	/* YugaByte don't use the heap buffer to cache the conflict tuple */
  	if (!IsYugaByteEnabled())
  		ReleaseBuffer(buffer);
  	return true;
  }
  
  /*
   * Process BEFORE EACH STATEMENT triggers
   */
  static void
  fireBSTriggers(ModifyTableState *node)
  {
  	ModifyTable *plan = (ModifyTable *) node->ps.plan;
  	ResultRelInfo *resultRelInfo = node->resultRelInfo;
  
  	/*
  	 * If the node modifies a partitioned table, we must fire its triggers.
  	 * Note that in that case, node->resultRelInfo points to the first leaf
  	 * partition, not the root table.
  	 */
  	if (node->rootResultRelInfo != NULL)
  		resultRelInfo = node->rootResultRelInfo;
  
  	switch (node->operation)
  	{
  		case CMD_INSERT:
  			ExecBSInsertTriggers(node->ps.state, resultRelInfo);
  			if (plan->onConflictAction == ONCONFLICT_UPDATE)
  				ExecBSUpdateTriggers(node->ps.state,
  									 resultRelInfo);
  			break;
  		case CMD_UPDATE:
  			ExecBSUpdateTriggers(node->ps.state, resultRelInfo);
  			break;
  		case CMD_DELETE:
  			ExecBSDeleteTriggers(node->ps.state, resultRelInfo);
  			break;
  		default:
  			elog(ERROR, "unknown operation");
  			break;
  	}
  }
  
  /*
   * Return the target rel ResultRelInfo.
   *
   * This relation is the same as :
   * - the relation for which we will fire AFTER STATEMENT triggers.
   * - the relation into whose tuple format all captured transition tuples must
   *   be converted.
   * - the root partitioned table.
   */
  static ResultRelInfo *
  getTargetResultRelInfo(ModifyTableState *node)
  {
  	/*
  	 * Note that if the node modifies a partitioned table, node->resultRelInfo
  	 * points to the first leaf partition, not the root table.
  	 */
  	if (node->rootResultRelInfo != NULL)
  		return node->rootResultRelInfo;
  	else
  		return node->resultRelInfo;
  }
  
  /*
   * Process AFTER EACH STATEMENT triggers
   */
  static void
  fireASTriggers(ModifyTableState *node)
  {
  	ModifyTable *plan = (ModifyTable *) node->ps.plan;
  	ResultRelInfo *resultRelInfo = getTargetResultRelInfo(node);
  
  	switch (node->operation)
  	{
  		case CMD_INSERT:
  			if (plan->onConflictAction == ONCONFLICT_UPDATE)
  				ExecASUpdateTriggers(node->ps.state,
  									 resultRelInfo,
  									 node->mt_oc_transition_capture);
  			ExecASInsertTriggers(node->ps.state, resultRelInfo,
  								 node->mt_transition_capture);
  			break;
  		case CMD_UPDATE:
  			ExecASUpdateTriggers(node->ps.state, resultRelInfo,
  								 node->mt_transition_capture);
  			break;
  		case CMD_DELETE:
  			ExecASDeleteTriggers(node->ps.state, resultRelInfo,
  								 node->mt_transition_capture);
  			break;
  		default:
  			elog(ERROR, "unknown operation");
  			break;
  	}
  }
  
  /*
   * Set up the state needed for collecting transition tuples for AFTER
   * triggers.
   */
  static void
  ExecSetupTransitionCaptureState(ModifyTableState *mtstate, EState *estate)
  {
  	ModifyTable *plan = (ModifyTable *) mtstate->ps.plan;
  	ResultRelInfo *targetRelInfo = getTargetResultRelInfo(mtstate);
  
  	/* Check for transition tables on the directly targeted relation. */
  	mtstate->mt_transition_capture =
  		MakeTransitionCaptureState(targetRelInfo->ri_TrigDesc,
  								   RelationGetRelid(targetRelInfo->ri_RelationDesc),
  								   mtstate->operation);
  	if (plan->operation == CMD_INSERT &&
  		plan->onConflictAction == ONCONFLICT_UPDATE)
  		mtstate->mt_oc_transition_capture =
  			MakeTransitionCaptureState(targetRelInfo->ri_TrigDesc,
  									   RelationGetRelid(targetRelInfo->ri_RelationDesc),
  									   CMD_UPDATE);
  
  	/*
  	 * If we found that we need to collect transition tuples then we may also
  	 * need tuple conversion maps for any children that have TupleDescs that
  	 * aren't compatible with the tuplestores.  (We can share these maps
  	 * between the regular and ON CONFLICT cases.)
  	 */
  	if (mtstate->mt_transition_capture != NULL ||
  		mtstate->mt_oc_transition_capture != NULL)
  	{
  		ExecSetupChildParentMapForTcs(mtstate);
  
  		/*
  		 * Install the conversion map for the first plan for UPDATE and DELETE
  		 * operations.  It will be advanced each time we switch to the next
  		 * plan.  (INSERT operations set it every time, so we need not update
  		 * mtstate->mt_oc_transition_capture here.)
  		 */
  		if (mtstate->mt_transition_capture && mtstate->operation != CMD_INSERT)
  			mtstate->mt_transition_capture->tcs_map =
  				tupconv_map_for_subplan(mtstate, 0);
  	}
  }
  
  /*
   * ExecPrepareTupleRouting --- prepare for routing one tuple
   *
   * Determine the partition in which the tuple in slot is to be inserted,
   * and modify mtstate and estate to prepare for it.
   *
   * Caller must revert the estate changes after executing the insertion!
   * In mtstate, transition capture changes may also need to be reverted.
   *
   * Returns a slot holding the tuple of the partition rowtype.
   */
  static TupleTableSlot *
  ExecPrepareTupleRouting(ModifyTableState *mtstate,
  						EState *estate,
  						PartitionTupleRouting *proute,
  						ResultRelInfo *targetRelInfo,
  						TupleTableSlot *slot)
  {
  	ModifyTable *node;
  	int			partidx;
  	ResultRelInfo *partrel;
  	HeapTuple	tuple;
  	TupleConversionMap *map;
  
  	/*
  	 * Determine the target partition.  If ExecFindPartition does not find a
  	 * partition after all, it doesn't return here; otherwise, the returned
  	 * value is to be used as an index into the arrays for the ResultRelInfo
  	 * and TupleConversionMap for the partition.
  	 */
  	partidx = ExecFindPartition(targetRelInfo,
  								proute->partition_dispatch_info,
  								slot,
  								estate);
  	Assert(partidx >= 0 && partidx < proute->num_partitions);
  
  	/*
  	 * Get the ResultRelInfo corresponding to the selected partition; if not
  	 * yet there, initialize it.
  	 */
  	partrel = proute->partitions[partidx];
  	if (partrel == NULL)
  		partrel = ExecInitPartitionInfo(mtstate, targetRelInfo,
  										proute, estate,
  										partidx);
  
  	/*
  	 * Check whether the partition is routable if we didn't yet
  	 *
  	 * Note: an UPDATE of a partition key invokes an INSERT that moves the
  	 * tuple to a new partition.  This check would be applied to a subplan
  	 * partition of such an UPDATE that is chosen as the partition to route
  	 * the tuple to.  The reason we do this check here rather than in
  	 * ExecSetupPartitionTupleRouting is to avoid aborting such an UPDATE
  	 * unnecessarily due to non-routable subplan partitions that may not be
  	 * chosen for update tuple movement after all.
  	 */
  	if (!partrel->ri_PartitionReadyForRouting)
  	{
  		/* Verify the partition is a valid target for INSERT. */
  		CheckValidResultRel(partrel, CMD_INSERT);
  
  		/* Set up information needed for routing tuples to the partition. */
  		ExecInitRoutingInfo(mtstate, estate, proute, partrel, partidx);
  	}
  
  	/*
  	 * Make it look like we are inserting into the partition.
  	 */
  	estate->es_result_relation_info = partrel;
  
  	/* Get the heap tuple out of the given slot. */
  	tuple = ExecMaterializeSlot(slot);
  
  	/*
  	 * If we're capturing transition tuples, we might need to convert from the
  	 * partition rowtype to parent rowtype.
  	 */
  	if (mtstate->mt_transition_capture != NULL)
  	{
  		if (partrel->ri_TrigDesc &&
  			partrel->ri_TrigDesc->trig_insert_before_row)
  		{
  			/*
  			 * If there are any BEFORE triggers on the partition, we'll have
  			 * to be ready to convert their result back to tuplestore format.
  			 */
  			mtstate->mt_transition_capture->tcs_original_insert_tuple = NULL;
  			mtstate->mt_transition_capture->tcs_map =
  				TupConvMapForLeaf(proute, targetRelInfo, partidx);
  		}
  		else
  		{
  			/*
  			 * Otherwise, just remember the original unconverted tuple, to
  			 * avoid a needless round trip conversion.
  			 */
  			mtstate->mt_transition_capture->tcs_original_insert_tuple = tuple;
  			mtstate->mt_transition_capture->tcs_map = NULL;
  		}
  	}
  	if (mtstate->mt_oc_transition_capture != NULL)
  	{
  		mtstate->mt_oc_transition_capture->tcs_map =
  			TupConvMapForLeaf(proute, targetRelInfo, partidx);
  	}
  
  	/*
  	 * Convert the tuple, if necessary.
  	 */
      map = proute->parent_child_tupconv_maps[partidx];
      if (map != NULL)
      {
          TupleTableSlot *new_slot;
  
          Assert(proute->partition_tuple_slots != NULL &&
                proute->partition_tuple_slots[partidx] != NULL);
          new_slot = proute->partition_tuple_slots[partidx];
          slot = execute_attr_map_slot(map->attrMap, slot, new_slot);
      }
  
  	/* Initialize information needed to handle ON CONFLICT DO UPDATE. */
  	Assert(mtstate != NULL);
  	node = (ModifyTable *) mtstate->ps.plan;
  	if (node->onConflictAction == ONCONFLICT_UPDATE)
  	{
  		Assert(mtstate->mt_existing != NULL);
  		ExecSetSlotDescriptor(mtstate->mt_existing,
  							  RelationGetDescr(partrel->ri_RelationDesc));
  		Assert(mtstate->mt_conflproj != NULL);
  		ExecSetSlotDescriptor(mtstate->mt_conflproj,
  							  partrel->ri_onConflict->oc_ProjTupdesc);
  	}
  
  	/*
  	 * For a partitioned relation, table constraints (such as FK) are visible on a
  	 * target partition rather than an original insert target.
  	 * As such, we should reevaluate single-row transaction constraints after
  	 * we determine the concrete partition.
  	 */
  	if (estate->es_yb_is_single_row_modify_txn)
  	{
  		estate->es_yb_is_single_row_modify_txn = YBCIsSingleRowTxnCapableRel(partrel);
  	}
  
  	return slot;
  }
  
  /*
   * Initialize the child-to-root tuple conversion map array for UPDATE subplans.
   *
   * This map array is required to convert the tuple from the subplan result rel
   * to the target table descriptor. This requirement arises for two independent
   * scenarios:
   * 1. For update-tuple-routing.
   * 2. For capturing tuples in transition tables.
   */
  static void
  ExecSetupChildParentMapForSubplan(ModifyTableState *mtstate)
  {
  	ResultRelInfo *targetRelInfo = getTargetResultRelInfo(mtstate);
  	ResultRelInfo *resultRelInfos = mtstate->resultRelInfo;
  	TupleDesc	outdesc;
  	int			numResultRelInfos = mtstate->mt_nplans;
  	int			i;
  
  	/*
  	 * First check if there is already a per-subplan array allocated. Even if
  	 * there is already a per-leaf map array, we won't require a per-subplan
  	 * one, since we will use the subplan offset array to convert the subplan
  	 * index to per-leaf index.
  	 */
  	if (mtstate->mt_per_subplan_tupconv_maps ||
  		(mtstate->mt_partition_tuple_routing &&
  		 mtstate->mt_partition_tuple_routing->child_parent_tupconv_maps))
  		return;
  
  	/*
  	 * Build array of conversion maps from each child's TupleDesc to the one
  	 * used in the target relation.  The map pointers may be NULL when no
  	 * conversion is necessary, which is hopefully a common case.
  	 */
  
  	/* Get tuple descriptor of the target rel. */
  	outdesc = RelationGetDescr(targetRelInfo->ri_RelationDesc);
  
  	mtstate->mt_per_subplan_tupconv_maps = (TupleConversionMap **)
  		palloc(sizeof(TupleConversionMap *) * numResultRelInfos);
  
  	for (i = 0; i < numResultRelInfos; ++i)
  	{
  		mtstate->mt_per_subplan_tupconv_maps[i] =
  			convert_tuples_by_name(RelationGetDescr(resultRelInfos[i].ri_RelationDesc),
  								   outdesc,
  								   gettext_noop("could not convert row type"));
  	}
  }
  
  /*
   * Initialize the child-to-root tuple conversion map array required for
   * capturing transition tuples.
   *
   * The map array can be indexed either by subplan index or by leaf-partition
   * index.  For transition tables, we need a subplan-indexed access to the map,
   * and where tuple-routing is present, we also require a leaf-indexed access.
   */
  static void
  ExecSetupChildParentMapForTcs(ModifyTableState *mtstate)
  {
  	PartitionTupleRouting *proute = mtstate->mt_partition_tuple_routing;
  
  	/*
  	 * If partition tuple routing is set up, we will require partition-indexed
  	 * access. In that case, create the map array indexed by partition; we
  	 * will still be able to access the maps using a subplan index by
  	 * converting the subplan index to a partition index using
  	 * subplan_partition_offsets. If tuple routing is not set up, it means we
  	 * don't require partition-indexed access. In that case, create just a
  	 * subplan-indexed map.
  	 */
  	if (proute)
  	{
  		/*
  		 * If a partition-indexed map array is to be created, the subplan map
  		 * array has to be NULL.  If the subplan map array is already created,
  		 * we won't be able to access the map using a partition index.
  		 */
  		Assert(mtstate->mt_per_subplan_tupconv_maps == NULL);
  
  		ExecSetupChildParentMapForLeaf(proute);
  	}
  	else
  		ExecSetupChildParentMapForSubplan(mtstate);
  }
  
  /*
   * For a given subplan index, get the tuple conversion map.
   */
  static TupleConversionMap *
  tupconv_map_for_subplan(ModifyTableState *mtstate, int whichplan)
  {
  	/*
  	 * If a partition-index tuple conversion map array is allocated, we need
  	 * to first get the index into the partition array. Exactly *one* of the
  	 * two arrays is allocated. This is because if there is a partition array
  	 * required, we don't require subplan-indexed array since we can translate
  	 * subplan index into partition index. And, we create a subplan-indexed
  	 * array *only* if partition-indexed array is not required.
  	 */
  	if (mtstate->mt_per_subplan_tupconv_maps == NULL)
  	{
  		int			leaf_index;
  		PartitionTupleRouting *proute = mtstate->mt_partition_tuple_routing;
  
  		/*
  		 * If subplan-indexed array is NULL, things should have been arranged
  		 * to convert the subplan index to partition index.
  		 */
  		Assert(proute && proute->subplan_partition_offsets != NULL &&
  			   whichplan < proute->num_subplan_partition_offsets);
  
  		leaf_index = proute->subplan_partition_offsets[whichplan];
  
  		return TupConvMapForLeaf(proute, getTargetResultRelInfo(mtstate),
  								 leaf_index);
  	}
  	else
  	{
  		Assert(whichplan >= 0 && whichplan < mtstate->mt_nplans);
  		return mtstate->mt_per_subplan_tupconv_maps[whichplan];
  	}
  }
  
  /* ----------------------------------------------------------------
   *	   ExecModifyTable
   *
   *		Perform table modifications as required, and return RETURNING results
   *		if needed.
   * ----------------------------------------------------------------
   */
  static TupleTableSlot *
  ExecModifyTable(PlanState *pstate)
  {
  	ModifyTableState *node = castNode(ModifyTableState, pstate);
  	PartitionTupleRouting *proute = node->mt_partition_tuple_routing;
  	EState	   *estate = node->ps.state;
  	CmdType		operation = node->operation;
  	ResultRelInfo *saved_resultRelInfo;
  	ResultRelInfo *resultRelInfo;
  	PlanState  *subplanstate;
  	JunkFilter *junkfilter;
  	TupleTableSlot *slot;
  	TupleTableSlot *planSlot;
  	ItemPointer tupleid;
  	ItemPointerData tuple_ctid;
  	HeapTupleData oldtupdata;
  	HeapTuple	oldtuple;
  
  	CHECK_FOR_INTERRUPTS();
  
  	/*
  	 * This should NOT get called during EvalPlanQual; we should have passed a
  	 * subplan tree to EvalPlanQual, instead.  Use a runtime test not just
  	 * Assert because this condition is easy to miss in testing.  (Note:
  	 * although ModifyTable should not get executed within an EvalPlanQual
  	 * operation, we do have to allow it to be initialized and shut down in
  	 * case it is within a CTE subplan.  Hence this test must be here, not in
  	 * ExecInitModifyTable.)
  	 */
  	if (estate->es_epqTuple != NULL)
  		elog(ERROR, "ModifyTable should not be called during EvalPlanQual");
  
  	/*
  	 * If we've already completed processing, don't try to do more.  We need
  	 * this test because ExecPostprocessPlan might call us an extra time, and
  	 * our subplan's nodes aren't necessarily robust against being called
  	 * extra times.
  	 */
  	if (node->mt_done)
  		return NULL;
  
  	/*
  	 * On first call, fire BEFORE STATEMENT triggers before proceeding.
  	 */
  	if (node->fireBSTriggers)
  	{
  		fireBSTriggers(node);
  		node->fireBSTriggers = false;
  	}
  
  	/* Preload local variables */
  	resultRelInfo = node->resultRelInfo + node->mt_whichplan;
  	subplanstate = node->mt_plans[node->mt_whichplan];
  	junkfilter = resultRelInfo->ri_junkFilter;
  
  	/*
  	 * es_result_relation_info must point to the currently active result
  	 * relation while we are within this ModifyTable node.  Even though
  	 * ModifyTable nodes can't be nested statically, they can be nested
  	 * dynamically (since our subplan could include a reference to a modifying
  	 * CTE).  So we have to save and restore the caller's value.
  	 */
  	saved_resultRelInfo = estate->es_result_relation_info;
  
  	estate->es_result_relation_info = resultRelInfo;
  
  	/*
  	 * Fetch rows from subplan(s), and execute the required table modification
  	 * for each row.
  	 */
  	for (;;)
  	{
  		/*
  		 * Reset the per-output-tuple exprcontext.  This is needed because
  		 * triggers expect to use that context as workspace.  It's a bit ugly
  		 * to do this below the top level of the plan, however.  We might need
  		 * to rethink this later.
  		 */
  		ResetPerTupleExprContext(estate);
  
  		planSlot = ExecProcNode(subplanstate);
  
  		if (TupIsNull(planSlot))
  		{
  			/* advance to next subplan if any */
  			node->mt_whichplan++;
  			if (node->mt_whichplan < node->mt_nplans)
  			{
  				resultRelInfo++;
  				subplanstate = node->mt_plans[node->mt_whichplan];
  				junkfilter = resultRelInfo->ri_junkFilter;
  				estate->es_result_relation_info = resultRelInfo;
  				EvalPlanQualSetPlan(&node->mt_epqstate, subplanstate->plan,
  									node->mt_arowmarks[node->mt_whichplan]);
  				/* Prepare to convert transition tuples from this child. */
  				if (node->mt_transition_capture != NULL)
  				{
  					node->mt_transition_capture->tcs_map =
  						tupconv_map_for_subplan(node, node->mt_whichplan);
  				}
  				if (node->mt_oc_transition_capture != NULL)
  				{
  					node->mt_oc_transition_capture->tcs_map =
  						tupconv_map_for_subplan(node, node->mt_whichplan);
  				}
  				continue;
  			}
  			else
  				break;
  		}
  
  		/*
  		 * If resultRelInfo->ri_usesFdwDirectModify is true, all we need to do
  		 * here is compute the RETURNING expressions.
  		 */
  		if (resultRelInfo->ri_usesFdwDirectModify)
  		{
  			Assert(resultRelInfo->ri_projectReturning);
  
  			/*
  			 * A scan slot containing the data that was actually inserted,
  			 * updated or deleted has already been made available to
  			 * ExecProcessReturning by IterateDirectModify, so no need to
  			 * provide it here.
  			 */
  			slot = ExecProcessReturning(resultRelInfo, NULL, planSlot);
  
  			estate->es_result_relation_info = saved_resultRelInfo;
  			return slot;
  		}
  
  		EvalPlanQualSetSlot(&node->mt_epqstate, planSlot);
  		slot = planSlot;
  
  		tupleid = NULL;
  		oldtuple = NULL;
  		if (junkfilter != NULL)
  		{
  			/*
  			 * extract the 'ctid' or 'wholerow' junk attribute.
  			 */
  			if (operation == CMD_UPDATE || operation == CMD_DELETE)
  			{
  				char		relkind;
  				Datum		datum;
  				bool		isNull;
  				AttrNumber  resno;
  
  				relkind = resultRelInfo->ri_RelationDesc->rd_rel->relkind;
  				/*
  				 * For YugaByte relations extract the old row from the wholerow junk
  				 * attribute if needed.
  				 * 1. For tables with secondary indexes we need the (old) ybctid for
  				 *    removing old index entries (for UPDATE and DELETE)
  				 * 2. For tables with row triggers we need to pass the old row for
  				 *    trigger execution.
  				 */
  				if (IsYBRelation(resultRelInfo->ri_RelationDesc) &&
  					(YBCRelInfoHasSecondaryIndices(resultRelInfo) ||
  					YBRelHasOldRowTriggers(resultRelInfo->ri_RelationDesc,
  					                       operation)))
  				{
  					resno = ExecFindJunkAttribute(junkfilter, "wholerow");
  					datum = ExecGetJunkAttribute(slot, resno, &isNull);
  
  					/* shouldn't ever get a null result... */
  					if (isNull)
  						elog(ERROR, "wholerow is NULL");
  
  					oldtupdata.t_data = DatumGetHeapTupleHeader(datum);
  					oldtupdata.t_len =
  						HeapTupleHeaderGetDatumLength(oldtupdata.t_data);
  					ItemPointerSetInvalid(&(oldtupdata.t_self));
  					/* Historically, view triggers see invalid t_tableOid. */
  					oldtupdata.t_tableOid =
  							(relkind == RELKIND_VIEW) ? InvalidOid :
  							RelationGetRelid(resultRelInfo->ri_RelationDesc);
  
  					resno = ExecFindJunkAttribute(junkfilter, "ybctid");
  					datum = ExecGetJunkAttribute(slot, resno, &isNull);
  
  					/* shouldn't ever get a null result... */
  					if (isNull)
  						elog(ERROR, "ybctid is NULL");
  
  					oldtupdata.t_ybctid = datum;
  
  					oldtuple = &oldtupdata;
  				}
  				else if (relkind == RELKIND_RELATION || relkind == RELKIND_MATVIEW)
  				{
  					datum = ExecGetJunkAttribute(slot,
  												 junkfilter->jf_junkAttNo,
  												 &isNull);
  					/* shouldn't ever get a null result... */
  					if (isNull)
  						elog(ERROR, "ctid is NULL");
  
  					tupleid = (ItemPointer) DatumGetPointer(datum);
  					tuple_ctid = *tupleid;	/* be sure we don't free ctid!! */
  					tupleid = &tuple_ctid;
  				}
  
  				/*
  				 * Use the wholerow attribute, when available, to reconstruct
  				 * the old relation tuple.
  				 *
  				 * Foreign table updates have a wholerow attribute when the
  				 * relation has a row-level trigger.  Note that the wholerow
  				 * attribute does not carry system columns.  Foreign table
  				 * triggers miss seeing those, except that we know enough here
  				 * to set t_tableOid.  Quite separately from this, the FDW may
  				 * fetch its own junk attrs to identify the row.
  				 *
  				 * Other relevant relkinds, currently limited to views, always
  				 * have a wholerow attribute.
  				 */
  				else if (AttributeNumberIsValid(junkfilter->jf_junkAttNo))
  				{
  					datum = ExecGetJunkAttribute(slot,
  												 junkfilter->jf_junkAttNo,
  												 &isNull);
  					/* shouldn't ever get a null result... */
  					if (isNull)
  						elog(ERROR, "wholerow is NULL");
  
  					oldtupdata.t_data = DatumGetHeapTupleHeader(datum);
  					oldtupdata.t_len =
  						HeapTupleHeaderGetDatumLength(oldtupdata.t_data);
  					ItemPointerSetInvalid(&(oldtupdata.t_self));
  					/* Historically, view triggers see invalid t_tableOid. */
  					oldtupdata.t_tableOid =
  						(relkind == RELKIND_VIEW) ? InvalidOid :
  						RelationGetRelid(resultRelInfo->ri_RelationDesc);
  
  					oldtuple = &oldtupdata;
  				}
  				else
  					Assert(relkind == RELKIND_FOREIGN_TABLE);
  			}
  
  			/*
  			 * apply the junkfilter if needed.
  			 */
  			if (operation != CMD_DELETE)
  				slot = ExecFilterJunk(junkfilter, slot);
  		}
  
  		switch (operation)
  		{
  			case CMD_INSERT:
  				if (!proute)
  				{
  					slot = ExecInsert(node, slot, planSlot,
  									  estate, node->canSetTag);
  				}
  				else
  				{
  					bool prev_yb_is_single_row_modify_txn =
  							estate->es_yb_is_single_row_modify_txn;
  
  					/* Prepare for tuple routing. */
  					slot = ExecPrepareTupleRouting(node, estate, proute,
  												   resultRelInfo, slot);
  
  					slot = ExecInsert(node, slot, planSlot,
  									  estate, node->canSetTag);
  
  					/* Revert ExecPrepareTupleRouting's state change. */
  					estate->es_result_relation_info = resultRelInfo;
  					estate->es_yb_is_single_row_modify_txn = prev_yb_is_single_row_modify_txn;
  				}
  				break;
  			case CMD_UPDATE:
  				slot = ExecUpdate(node, tupleid, oldtuple, slot, planSlot,
  								  &node->mt_epqstate, estate, node->canSetTag);
  				break;
  			case CMD_DELETE:
  				slot = ExecDelete(node, tupleid, oldtuple, planSlot,
  								  &node->mt_epqstate, estate,
  								  true, node->canSetTag,
  								  false /* changingPart */ , NULL, NULL);
  				break;
  			default:
  				elog(ERROR, "unknown operation");
  				break;
  		}
  
  		/*
  		 * If we got a RETURNING result, return it to caller.  We'll continue
  		 * the work on next call.
  		 */
  		if (slot)
  		{
  			estate->es_result_relation_info = saved_resultRelInfo;
  			return slot;
  		}
  	}
  
  	/* Restore es_result_relation_info before exiting */
  	estate->es_result_relation_info = saved_resultRelInfo;
  
  	/*
  	 * We're done, but fire AFTER STATEMENT triggers before exiting.
  	 */
  	fireASTriggers(node);
  
  	node->mt_done = true;
  
  	return NULL;
  }
  
  /* ----------------------------------------------------------------
   *		ExecInitModifyTable
   * ----------------------------------------------------------------
   */
  ModifyTableState *
  ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
  {
  	ModifyTableState *mtstate;
  	CmdType		operation = node->operation;
  	int			nplans = list_length(node->plans);
  	ResultRelInfo *saved_resultRelInfo;
  	ResultRelInfo *resultRelInfo;
  	Plan	   *subplan;
  	ListCell   *l;
  	int			i;
  	Relation	rel;
  	bool		update_tuple_routing_needed = node->partColsUpdated;
  
  	/* check for unsupported flags */
  	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
  
  	/*
  	 * create state structure
  	 */
  	mtstate = makeNode(ModifyTableState);
  	mtstate->ps.plan = (Plan *) node;
  	mtstate->ps.state = estate;
  	mtstate->ps.ExecProcNode = ExecModifyTable;
  
  	mtstate->operation = operation;
  	mtstate->canSetTag = node->canSetTag;
  	mtstate->mt_done = false;
  
  	mtstate->mt_plans = (PlanState **) palloc0(sizeof(PlanState *) * nplans);
  	mtstate->resultRelInfo = estate->es_result_relations + node->resultRelIndex;
  	mtstate->yb_mt_is_single_row_update_or_delete = YBCIsSingleRowUpdateOrDelete(node);
  
  	/* If modifying a partitioned table, initialize the root table info */
  	if (node->rootResultRelIndex >= 0)
  		mtstate->rootResultRelInfo = estate->es_root_result_relations +
  			node->rootResultRelIndex;
  
  	mtstate->mt_arowmarks = (List **) palloc0(sizeof(List *) * nplans);
  	mtstate->mt_nplans = nplans;
  
  	/* set up epqstate with dummy subplan data for the moment */
  	EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, NIL, node->epqParam);
  	mtstate->fireBSTriggers = true;
  
  	/*
  	 * call ExecInitNode on each of the plans to be executed and save the
  	 * results into the array "mt_plans".  This is also a convenient place to
  	 * verify that the proposed target relations are valid and open their
  	 * indexes for insertion of new index entries.  Note we *must* set
  	 * estate->es_result_relation_info correctly while we initialize each
  	 * sub-plan; ExecContextForcesOids depends on that!
  	 */
  	saved_resultRelInfo = estate->es_result_relation_info;
  
  	resultRelInfo = mtstate->resultRelInfo;
  	i = 0;
  	foreach(l, node->plans)
  	{
  		subplan = (Plan *) lfirst(l);
  
  		/* Initialize the usesFdwDirectModify flag */
  		resultRelInfo->ri_usesFdwDirectModify = bms_is_member(i,
  															  node->fdwDirectModifyPlans);
  
  		/*
  		 * Verify result relation is a valid target for the current operation
  		 */
  		CheckValidResultRel(resultRelInfo, operation);
  
  		/*
  		 * If there are indices on the result relation, open them and save
  		 * descriptors in the result relation info, so that we can add new
  		 * index entries for the tuples we add/update.  We need not do this
  		 * for a DELETE, however, since deletion doesn't affect indexes. Also,
  		 * inside an EvalPlanQual operation, the indexes might be open
  		 * already, since we share the resultrel state with the original
  		 * query.
  		 *
  		 * For a YugaByte table, we need to update the secondary indices for
  		 * all of the INSERT, UPDATE, and DELETE statements. The ON CONFLICT UPDATE
  		 * execution also needs to process primary key index.
  		 */
  		if ((IsYBRelation(resultRelInfo->ri_RelationDesc) ?
  				 (YBRelHasSecondaryIndices(resultRelInfo->ri_RelationDesc) ||
  					node->onConflictAction != ONCONFLICT_NONE) :
  				 (resultRelInfo->ri_RelationDesc->rd_rel->relhasindex &&
  					operation != CMD_DELETE)) &&
  				resultRelInfo->ri_IndexRelationDescs == NULL)
  			ExecOpenIndices(resultRelInfo,
  							node->onConflictAction != ONCONFLICT_NONE);
  
  		/*
  		 * If this is an UPDATE and a BEFORE UPDATE trigger is present, the
  		 * trigger itself might modify the partition-key values. So arrange
  		 * for tuple routing.
  		 */
  		if (resultRelInfo->ri_TrigDesc &&
  			resultRelInfo->ri_TrigDesc->trig_update_before_row &&
  			operation == CMD_UPDATE)
  			update_tuple_routing_needed = true;
  
  		/* Now init the plan for this result rel */
  		estate->es_result_relation_info = resultRelInfo;
  		mtstate->mt_plans[i] = ExecInitNode(subplan, estate, eflags);
  
  		/* Also let FDWs init themselves for foreign-table result rels */
  		if (!resultRelInfo->ri_usesFdwDirectModify &&
  			resultRelInfo->ri_FdwRoutine != NULL &&
  			resultRelInfo->ri_FdwRoutine->BeginForeignModify != NULL)
  		{
  			List	   *fdw_private = (List *) list_nth(node->fdwPrivLists, i);
  
  			resultRelInfo->ri_FdwRoutine->BeginForeignModify(mtstate,
  															 resultRelInfo,
  															 fdw_private,
  															 i,
  															 eflags);
  		}
  
  		resultRelInfo++;
  		i++;
  	}
  
  	estate->es_result_relation_info = saved_resultRelInfo;
  
  	/* Get the target relation */
  	rel = (getTargetResultRelInfo(mtstate))->ri_RelationDesc;
  
  	/*
  	 * If it's not a partitioned table after all, UPDATE tuple routing should
  	 * not be attempted.
  	 */
  	if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
  		update_tuple_routing_needed = false;
  
  	/*
  	 * Build state for tuple routing if it's an INSERT or if it's an UPDATE of
  	 * partition key.
  	 */
  	if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
  		(operation == CMD_INSERT || update_tuple_routing_needed))
  		mtstate->mt_partition_tuple_routing =
  			ExecSetupPartitionTupleRouting(mtstate, rel);
  
  	/*
  	 * Build state for collecting transition tuples.  This requires having a
  	 * valid trigger query context, so skip it in explain-only mode.
  	 */
  	if (!(eflags & EXEC_FLAG_EXPLAIN_ONLY))
  		ExecSetupTransitionCaptureState(mtstate, estate);
  
  	/*
  	 * Construct mapping from each of the per-subplan partition attnos to the
  	 * root attno.  This is required when during update row movement the tuple
  	 * descriptor of a source partition does not match the root partitioned
  	 * table descriptor.  In such a case we need to convert tuples to the root
  	 * tuple descriptor, because the search for destination partition starts
  	 * from the root.  Skip this setup if it's not a partition key update.
  	 */
  	if (update_tuple_routing_needed)
  		ExecSetupChildParentMapForSubplan(mtstate);
  
  	/*
  	 * Initialize any WITH CHECK OPTION constraints if needed.
  	 */
  	resultRelInfo = mtstate->resultRelInfo;
  	i = 0;
  	foreach(l, node->withCheckOptionLists)
  	{
  		List	   *wcoList = (List *) lfirst(l);
  		List	   *wcoExprs = NIL;
  		ListCell   *ll;
  
  		foreach(ll, wcoList)
  		{
  			WithCheckOption *wco = (WithCheckOption *) lfirst(ll);
  			ExprState  *wcoExpr = ExecInitQual((List *) wco->qual,
  											   &mtstate->ps);
  
  			wcoExprs = lappend(wcoExprs, wcoExpr);
  		}
  
  		resultRelInfo->ri_WithCheckOptions = wcoList;
  		resultRelInfo->ri_WithCheckOptionExprs = wcoExprs;
  		resultRelInfo++;
  		i++;
  	}
  
  	/*
  	 * Initialize RETURNING projections if needed.
  	 */
  	if (node->returningLists)
  	{
  		TupleTableSlot *slot;
  		ExprContext *econtext;
  
  		/*
  		 * Initialize result tuple slot and assign its rowtype using the first
  		 * RETURNING list.  We assume the rest will look the same.
  		 */
  		mtstate->ps.plan->targetlist = (List *) linitial(node->returningLists);
  
  		/* Set up a slot for the output of the RETURNING projection(s) */
  		ExecInitResultTupleSlotTL(&mtstate->ps);
  		slot = mtstate->ps.ps_ResultTupleSlot;
  
  		/* Need an econtext too */
  		if (mtstate->ps.ps_ExprContext == NULL)
  			ExecAssignExprContext(estate, &mtstate->ps);
  		econtext = mtstate->ps.ps_ExprContext;
  
  		/*
  		 * Build a projection for each result rel.
  		 */
  		resultRelInfo = mtstate->resultRelInfo;
  		foreach(l, node->returningLists)
  		{
  			List	   *rlist = (List *) lfirst(l);
  
  			resultRelInfo->ri_returningList = rlist;
  			resultRelInfo->ri_projectReturning =
  				ExecBuildProjectionInfo(rlist, econtext, slot, &mtstate->ps,
  										resultRelInfo->ri_RelationDesc->rd_att);
  			resultRelInfo++;
  		}
  	}
  	else
  	{
  		/*
  		 * We still must construct a dummy result tuple type, because InitPlan
  		 * expects one (maybe should change that?).
  		 */
  		mtstate->ps.plan->targetlist = NIL;
  		ExecInitResultTypeTL(&mtstate->ps);
  
  		mtstate->ps.ps_ExprContext = NULL;
  	}
  
  	/* Set the list of arbiter indexes if needed for ON CONFLICT */
  	resultRelInfo = mtstate->resultRelInfo;
  	if (node->onConflictAction != ONCONFLICT_NONE)
  		resultRelInfo->ri_onConflictArbiterIndexes = node->arbiterIndexes;
  
  	/*
  	 * If needed, Initialize target list, projection and qual for ON CONFLICT
  	 * DO UPDATE.
  	 */
  	if (node->onConflictAction == ONCONFLICT_UPDATE)
  	{
  		OnConflictSetState *onconfl = makeNode(OnConflictSetState);
  		ExprContext *econtext;
  		TupleDesc	relationDesc;
  
  		/* insert may only have one plan, inheritance is not expanded */
  		Assert(nplans == 1);
  
  		/* already exists if created by RETURNING processing above */
  		if (mtstate->ps.ps_ExprContext == NULL)
  			ExecAssignExprContext(estate, &mtstate->ps);
  
  		econtext = mtstate->ps.ps_ExprContext;
  		relationDesc = resultRelInfo->ri_RelationDesc->rd_att;
  
  		/*
  		 * Initialize slot for the existing tuple.  If we'll be performing
  		 * tuple routing, the tuple descriptor to use for this will be
  		 * determined based on which relation the update is actually applied
  		 * to, so we don't set its tuple descriptor here.
  		 */
  		mtstate->mt_existing =
  			ExecInitExtraTupleSlot(mtstate->ps.state,
  								   mtstate->mt_partition_tuple_routing ?
  								   NULL : relationDesc);
  
  		/* carried forward solely for the benefit of explain */
  		mtstate->mt_excludedtlist = node->exclRelTlist;
  
  		/* create state for DO UPDATE SET operation */
  		resultRelInfo->ri_onConflict = onconfl;
  
  		/*
  		 * Create the tuple slot for the UPDATE SET projection.
  		 *
  		 * Just like mt_existing above, we leave it without a tuple descriptor
  		 * in the case of partitioning tuple routing, so that it can be
  		 * changed by ExecPrepareTupleRouting.  In that case, we still save
  		 * the tupdesc in the parent's state: it can be reused by partitions
  		 * with an identical descriptor to the parent.
  		 */
  		mtstate->mt_conflproj =
  			ExecInitExtraTupleSlot(mtstate->ps.state,
  								   mtstate->mt_partition_tuple_routing ?
  								   NULL : relationDesc);
  		onconfl->oc_ProjTupdesc = relationDesc;
  
  		/*
  		 * The onConflictSet tlist should already have been adjusted to emit
  		 * the table's exact column list.  It could also contain resjunk
  		 * columns, which should be evaluated but not included in the
  		 * projection result.
  		 */
  		ExecCheckPlanOutput(resultRelInfo->ri_RelationDesc,
  							node->onConflictSet);
  
  		/* build UPDATE SET projection state */
  		onconfl->oc_ProjInfo =
  			ExecBuildProjectionInfoExt(node->onConflictSet, econtext,
  									   mtstate->mt_conflproj, false,
  									   &mtstate->ps,
  									   relationDesc);
  
  		/* initialize state to evaluate the WHERE clause, if any */
  		if (node->onConflictWhere)
  		{
  			ExprState  *qualexpr;
  
  			qualexpr = ExecInitQual((List *) node->onConflictWhere,
  									&mtstate->ps);
  			onconfl->oc_WhereClause = qualexpr;
  		}
  	}
  
  	/*
  	 * If we have any secondary relations in an UPDATE or DELETE, they need to
  	 * be treated like non-locked relations in SELECT FOR UPDATE, ie, the
  	 * EvalPlanQual mechanism needs to be told about them.  Locate the
  	 * relevant ExecRowMarks.
  	 */
  	foreach(l, node->rowMarks)
  	{
  		PlanRowMark *rc = lfirst_node(PlanRowMark, l);
  		ExecRowMark *erm;
  
  		/* ignore "parent" rowmarks; they are irrelevant at runtime */
  		if (rc->isParent)
  			continue;
  
  		/* find ExecRowMark (same for all subplans) */
  		erm = ExecFindRowMark(estate, rc->rti, false);
  
  		/* build ExecAuxRowMark for each subplan */
  		for (i = 0; i < nplans; i++)
  		{
  			ExecAuxRowMark *aerm;
  
  			subplan = mtstate->mt_plans[i]->plan;
  			aerm = ExecBuildAuxRowMark(erm, subplan->targetlist);
  			mtstate->mt_arowmarks[i] = lappend(mtstate->mt_arowmarks[i], aerm);
  		}
  	}
  
  	/* select first subplan */
  	mtstate->mt_whichplan = 0;
  	subplan = (Plan *) linitial(node->plans);
  	EvalPlanQualSetPlan(&mtstate->mt_epqstate, subplan,
  						mtstate->mt_arowmarks[0]);
  
  	/*
  	 * Initialize the junk filter(s) if needed.  INSERT queries need a filter
  	 * if there are any junk attrs in the tlist.  UPDATE and DELETE always
  	 * need a filter, since there's always at least one junk attribute present
  	 * --- no need to look first.  Typically, this will be a 'ctid' or
  	 * 'wholerow' attribute, but in the case of a foreign data wrapper it
  	 * might be a set of junk attributes sufficient to identify the remote
  	 * row.
  	 *
  	 * If there are multiple result relations, each one needs its own junk
  	 * filter.  Note multiple rels are only possible for UPDATE/DELETE, so we
  	 * can't be fooled by some needing a filter and some not.
  	 *
  	 * This section of code is also a convenient place to verify that the
  	 * output of an INSERT or UPDATE matches the target table(s).
  	 */
  	{
  		bool		junk_filter_needed = false;
  
  		switch (operation)
  		{
  			case CMD_INSERT:
  				foreach(l, subplan->targetlist)
  				{
  					TargetEntry *tle = (TargetEntry *) lfirst(l);
  
  					if (tle->resjunk)
  					{
  						junk_filter_needed = true;
  						break;
  					}
  				}
  				break;
  			case CMD_UPDATE:
  			case CMD_DELETE:
  				/*
  				 * If it's a YB single row UPDATE/DELETE we do not perform an
  				 * initial scan to populate the ybctid, so there is no junk
  				 * attribute to extract.
  				 */
  				junk_filter_needed = !mtstate->yb_mt_is_single_row_update_or_delete;
  				break;
  			default:
  				elog(ERROR, "unknown operation");
  				break;
  		}
  
  		if (junk_filter_needed)
  		{
  			resultRelInfo = mtstate->resultRelInfo;
  			for (i = 0; i < nplans; i++)
  			{
  				JunkFilter *j;
  
  				subplan = mtstate->mt_plans[i]->plan;
  				if (operation == CMD_INSERT || operation == CMD_UPDATE)
  					ExecCheckPlanOutput(resultRelInfo->ri_RelationDesc,
  										subplan->targetlist);
  
  				j = ExecInitJunkFilter(subplan->targetlist,
  									   resultRelInfo->ri_RelationDesc->rd_att->tdhasoid,
  									   ExecInitExtraTupleSlot(estate, NULL));
  
  				if (operation == CMD_UPDATE || operation == CMD_DELETE)
  				{
  					/* For UPDATE/DELETE, find the appropriate junk attr now */
  					char		relkind;
  
  					relkind = resultRelInfo->ri_RelationDesc->rd_rel->relkind;
  					if (IsYBRelation(rel))
  					{
  						j->jf_junkAttNo = ExecFindJunkAttribute(j, "ybctid");
  						if (!AttributeNumberIsValid(j->jf_junkAttNo)) {
  							elog(ERROR, "could not find junk ybctid column");
  						}
  					}
  					else if (relkind == RELKIND_RELATION ||
  						relkind == RELKIND_MATVIEW ||
  						relkind == RELKIND_PARTITIONED_TABLE)
  					{
  						j->jf_junkAttNo = ExecFindJunkAttribute(j, "ctid");
  						if (!AttributeNumberIsValid(j->jf_junkAttNo))
  							elog(ERROR, "could not find junk ctid column");
  					}
  					else if (relkind == RELKIND_FOREIGN_TABLE)
  					{
  						/*
  						 * When there is a row-level trigger, there should be
  						 * a wholerow attribute.
  						 */
  						j->jf_junkAttNo = ExecFindJunkAttribute(j, "wholerow");
  					}
  					else
  					{
  						j->jf_junkAttNo = ExecFindJunkAttribute(j, "wholerow");
  						if (!AttributeNumberIsValid(j->jf_junkAttNo))
  							elog(ERROR, "could not find junk wholerow column");
  					}
  				}
  
  				resultRelInfo->ri_junkFilter = j;
  				resultRelInfo++;
  			}
  		}
  		else
  		{
  			if (operation == CMD_INSERT)
  				ExecCheckPlanOutput(mtstate->resultRelInfo->ri_RelationDesc,
  									subplan->targetlist);
  		}
  	}
  
  	/*
  	 * Set up a tuple table slot for use for trigger output tuples. In a plan
  	 * containing multiple ModifyTable nodes, all can share one such slot, so
  	 * we keep it in the estate.
  	 */
  	if (estate->es_trig_tuple_slot == NULL)
  		estate->es_trig_tuple_slot = ExecInitExtraTupleSlot(estate, NULL);
  
  	/*
  	 * Lastly, if this is not the primary (canSetTag) ModifyTable node, add it
  	 * to estate->es_auxmodifytables so that it will be run to completion by
  	 * ExecPostprocessPlan.  (It'd actually work fine to add the primary
  	 * ModifyTable node too, but there's no need.)  Note the use of lcons not
  	 * lappend: we need later-initialized ModifyTable nodes to be shut down
  	 * before earlier ones.  This ensures that we don't throw away RETURNING
  	 * rows that need to be seen by a later CTE subplan.
  	 */
  	if (!mtstate->canSetTag)
  		estate->es_auxmodifytables = lcons(mtstate,
  										   estate->es_auxmodifytables);
  
  	return mtstate;
  }
  
  /* ----------------------------------------------------------------
   *		ExecEndModifyTable
   *
   *		Shuts down the plan.
   *
   *		Returns nothing of interest.
   * ----------------------------------------------------------------
   */
  void
  ExecEndModifyTable(ModifyTableState *node)
  {
  	int			i;
  
  	/*
  	 * Allow any FDWs to shut down
  	 */
  	for (i = 0; i < node->mt_nplans; i++)
  	{
  		ResultRelInfo *resultRelInfo = node->resultRelInfo + i;
  
  		if (!resultRelInfo->ri_usesFdwDirectModify &&
  			resultRelInfo->ri_FdwRoutine != NULL &&
  			resultRelInfo->ri_FdwRoutine->EndForeignModify != NULL)
  			resultRelInfo->ri_FdwRoutine->EndForeignModify(node->ps.state,
  														   resultRelInfo);
  	}
  
  	/* Close all the partitioned tables, leaf partitions, and their indices */
  	if (node->mt_partition_tuple_routing)
  		ExecCleanupTupleRouting(node, node->mt_partition_tuple_routing);
  
  	/*
  	 * Free the exprcontext
  	 */
  	ExecFreeExprContext(&node->ps);
  
  	/*
  	 * clean out the tuple table
  	 */
  	if (node->ps.ps_ResultTupleSlot)
  		ExecClearTuple(node->ps.ps_ResultTupleSlot);
  
  	/*
  	 * Terminate EPQ execution if active
  	 */
  	EvalPlanQualEnd(&node->mt_epqstate);
  
  	/*
  	 * shut down subplans
  	 */
  	for (i = 0; i < node->mt_nplans; i++)
  		ExecEndNode(node->mt_plans[i]);
  }
  
  void
  ExecReScanModifyTable(ModifyTableState *node)
  {
  	/*
  	 * Currently, we don't need to support rescan on ModifyTable nodes. The
  	 * semantics of that would be a bit debatable anyway.
  	 */
  	elog(ERROR, "ExecReScanModifyTable is not implemented");
  }
  