database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-19 13:42:17 +03:00
Code Activity

Revert "Show index search count in EXPLAIN ANALYZE."

Browse Source 
This reverts commit 5ead85fbc8.

This commit shows test failures with debug_parallel_query=regress.  The
underlying issue needs to be debugged, so revert for now.
This commit is contained in:
Peter Geoghegan
2025-03-05 10:27:31 -05:00
parent 4603903d29
commit d00107cd63
22 changed files with 49 additions and 310 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
doc/src/sgml/monitoring.sgml
View File

@@ -4234,32 +4234,16 @@ description | Waiting for a newly initialized WAL file to reach durable storage
<note>
<para>
Index scans may sometimes perform multiple index searches per execution.
Each index search increments <structname>pg_stat_all_indexes</structname>.<structfield>idx_scan</structfield>,
Queries that use certain <acronym>SQL</acronym> constructs to search for
rows matching any value out of a list or array of multiple scalar values
(see <xref linkend="functions-comparisons"/>) perform multiple
<quote>primitive</quote> index scans (up to one primitive scan per scalar
value) during query execution. Each internal primitive index scan
increments <structname>pg_stat_all_indexes</structname>.<structfield>idx_scan</structfield>,
so it's possible for the count of index scans to significantly exceed the
total number of index scan executor node executions.
</para>
<para>
This can happen with queries that use certain <acronym>SQL</acronym>
constructs to search for rows matching any value out of a list or array of
multiple scalar values (see <xref linkend="functions-comparisons"/>). It
can also happen to queries with a
<literal><replaceable>column_name</replaceable> =
<replaceable>value1</replaceable> OR
<replaceable>column_name</replaceable> =
<replaceable>value2</replaceable> ...</literal> construct, though only
when the optimizer transforms the construct into an equivalent
multi-valued array representation.
</para>
</note>
<tip>
<para>
<command>EXPLAIN ANALYZE</command> outputs the total number of index
searches performed by each index scan node. See
<xref linkend="using-explain-analyze"/> for an example demonstrating how
this works.
</para>
</tip>
</sect2>