anchor.diff:  * Communication
   * Exchange
   * Transactions
  +* SQL queries
   
   
   To view traces, you must export them into an external system.
  
positive.code: * `EXCHANGE` —  exchange events
  * `COMMUNICATION` — communication events
  * `TX` — transactions
  
  The `--sampling-rate` is the probabilistic sampling rate, a number between `0` and `1`:
  
  
negative.code: 
  image::images/span.png[Span]
  
  
  == Tracing SQL Queries
  
  To enable SQL queries tracing, use `SQL` as a value of the `scope` parameter during the link:https://ignite.apache.org/docs/latest/monitoring-metrics/tracing#enabling-trace-sampling[trace sampling configuration, window=_blank].
  If tracing of SQL queries is enabled, execution of each SQL query on any cluster node will produce a separate trace.
  
  [IMPORTANT]
  ====
  [discrete]
  Enabling tracing for SQL queries imposes a severe degradation on SQL engine performance.
  ====
  
  The table below provides descriptions, a list of tags, and annotations for each span that can be a part of the SQL query trace tree.
  
  [NOTE]
  ====
  [discrete]
  Depending on the SQL query type and its execution plan, some spans may not be present in the SQL query span tree.
  ====
  
  [cols="2,5,5",opts="header"]
  |===
  |Span Name | Description | Tags and Annotations
  | sql.query | Execution of an SQL query from the moment of registration until the used resources on the query initiator node are released a|
  * sql.query.text - SQL query text
  * sql.schema - SQL schema
  | sql.cursor.open | SQL query cursor opening |
  | sql.cursor.close | SQL query cursor closure |
  | sql.cursor.cancel | SQL query cursor cancellation |
  | sql.query.parse | Parsing of SQL query a|
  * sql.parser.cache.hit - Whether parsing of the SQL query was skipped due to the cached result
  | sql.query.execute.request | Processing of SQL query execution request a|
  * sql.query.text - SQL query text
  | sql.next.page.request | Processing of the request for obtaining the next page of local SQL query execution result  |
  | sql.page.response | Processing of the message with a node local SQL query execution result page |
  | sql.query.execute | Execution of query by H2 SQL engine a|
  * sql.query.text - SQL query text
  | sql.page.prepare | Reading rows from the cursor and preparing a result page a|
  * sql.page.rows - Number of rows that a result page contains
  | sql.fail.response | Processing of a message that indicates failure of SQL query execution |
  | sql.dml.query.execute.request | Processing of SQL DML query execution request a|
  * sql.query.text - SQL query text
  | sql.dml.query.response | Processing of SQL DML query execution result by query initiator node |
  | sql.query.cancel.request | Processing of SQL query cancel request |
  | sql.iterator.open | SQL query iterator opening |
  | sql.iterator.close | SQL query iterator closure |
  | sql.page.fetch | Fetching SQL query result page a|
  * sql.page.rows - Number of rows that result page contains
  | sql.page.wait | Waiting for SQL query results page to be received from remote node |
  | sql.index.range.request | Processing SQL index range request a|
  * sql.index - SQL index name
  * sql.table - SQL table name
  * sql.index.range.rows - Number of rows that an index range request result contains
  | sql.index.range.response | Processing SQL index range responce |
  | sql.dml.query.execute |  Execution of SQL DML query |
  | sql.command.query.execute | Execution of an SQL command query, which is either a DDL query or an Ignite native command |
  | sql.partitions.reserve | Reservation of data partitions used to execute a query a|
  * Annotation message that indicates reservation of data partitions for a particular cache - `Cache partitions were reserved [cache=<name of the cache>, partitions=[<partitions numbers>]`
  | sql.cache.update | Cache update as a result of SQL DML query execution a|
  * sql.cache.updates - Number of cache entries to be updated as a result of DML query
  | sql.batch.process| Processing of SQL batch update |
  |===
  
  ////
  TODO: describe annotations and tags
  === Annotations
  