text: /* -------------------------------------------------------------------------
   *
   * tuplestore.h
   *	  Generalized routines for temporary tuple storage.
   *
   * This module handles temporary storage of tuples for purposes such
   * as Materialize nodes, hashjoin batch files, etc.  It is essentially
   * a dumbed-down version of tuplesort.c; it does no sorting of tuples
   * but can only store and regurgitate a sequence of tuples.  However,
   * because no sort is required, it is allowed to start reading the sequence
   * before it has all been written.	This is particularly useful for cursors,
   * because it allows random access within the already-scanned portion of
   * a query without having to process the underlying scan to completion.
   * Also, it is possible to support multiple independent read pointers.
   *
   * A temporary file is used to handle the data if it exceeds the
   * space limit specified by the caller.
   *
   * Beginning in Postgres 8.2, what is stored is just MinimalTuples;
   * callers cannot expect valid system columns in regurgitated tuples.
   * Also, we have changed the API to return tuples in TupleTableSlots,
   * so that there is a check to prevent attempted access to system columns.
   *
   * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * src/include/utils/tuplestore.h
   *
   * -------------------------------------------------------------------------
   */
  #ifndef TUPLESTORE_H
  #define TUPLESTORE_H
  
  #include "executor/tuptable.h"
  
  /* Tuplestorestate is an opaque type whose details are not known outside
   * tuplestore.c.
   */
  typedef struct Tuplestorestate Tuplestorestate;
  
  /*
   * Currently we only need to store MinimalTuples, but it would be easy
   * to support the same behavior for IndexTuples and/or bare Datums.
   */
  
  extern Tuplestorestate* tuplestore_begin_heap(bool randomAccess, bool interXact, int maxKBytes, int maxMem = 0,
      int planId = 0, int dop = 1, bool isAddMemCtl = false);
  
  extern void tuplestore_set_eflags(Tuplestorestate* state, int eflags);
  
  extern void tuplestore_puttupleslot(Tuplestorestate* state, TupleTableSlot* slot);
  extern void tuplestore_puttuple(Tuplestorestate* state, HeapTuple tuple);
  extern void tuplestore_putvalues(Tuplestorestate* state, TupleDesc tdesc, Datum* values, const bool* isnull);
  
  /* tuplestore_donestoring() used to be required, but is no longer used */
  #define tuplestore_donestoring(state) ((void)0)
  
  extern int tuplestore_alloc_read_pointer(Tuplestorestate* state, int eflags);
  
  extern void tuplestore_select_read_pointer(Tuplestorestate* state, int ptr);
  
  extern void tuplestore_copy_read_pointer(Tuplestorestate* state, int srcptr, int destptr);
  
  extern void tuplestore_trim(Tuplestorestate* state);
  
  extern bool tuplestore_in_memory(Tuplestorestate* state);
  
  extern bool tuplestore_gettupleslot(Tuplestorestate* state, bool forward, bool copy, TupleTableSlot* slot);
  extern bool tuplestore_advance(Tuplestorestate* state, bool forward);
  
  extern bool tuplestore_ateof(Tuplestorestate* state);
  
  extern void tuplestore_rescan(Tuplestorestate* state);
  
  extern void tuplestore_clear(Tuplestorestate* state);
  
  extern void tuplestore_end(Tuplestorestate* state);
  
  extern int64 tuplestore_get_avgwidth(Tuplestorestate* state);
  extern bool tuplestore_get_busy_status(Tuplestorestate* state);
  extern int tuplestore_get_spread_num(Tuplestorestate* state);
  
  #endif /* TUPLESTORE_H */
  