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| author | David Rowley <drowley@postgresql.org> | 2023-06-22 12:45:30 +1200 |
|---|---|---|
| committer | David Rowley <drowley@postgresql.org> | 2023-06-22 12:45:50 +1200 |
| commit | c2d35bb88eab99fd81198fa4caee004fb8997c73 (patch) | |
| tree | 1c771a0e4b24a7a8809b434b05b6a52da4aae98b | |
| parent | 5f0762f14754597724c24cf6517fe4fe6412a6f9 (diff) | |
| download | postgresql-c2d35bb88eab99fd81198fa4caee004fb8997c73.tar.gz postgresql-c2d35bb88eab99fd81198fa4caee004fb8997c73.zip | |
Doc: mention that extended stats aren't used for joins
Statistics defined by the CREATE STATISTICS command are only used to
assist with the selectivity estimations of base relations, never for
joins. Here we mention this fact in the notes section of the CREATE
STATISTICS command.
Discussion: https://postgr.es/m/CAApHDvrMuVgDOrmg_EtFDZ=AOovq6EsJNnHH1ddyZ8EqL4yzMw@mail.gmail.com
Backpatch-through: 11
| -rw-r--r-- | doc/src/sgml/ref/create_statistics.sgml | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/doc/src/sgml/ref/create_statistics.sgml b/doc/src/sgml/ref/create_statistics.sgml index 3a92fc55ede..d6b25ed2c9b 100644 --- a/doc/src/sgml/ref/create_statistics.sgml +++ b/doc/src/sgml/ref/create_statistics.sgml @@ -171,6 +171,12 @@ CREATE STATISTICS [ [ IF NOT EXISTS ] <replaceable class="parameter">statistics_ maintenance. Expression statistics are built automatically for each expression in the statistics object definition. </para> + + <para> + Extended statistics are not currently used by the planner for selectivity + estimations made for table joins. This limitation will likely be removed + in a future version of <productname>PostgreSQL</productname>. + </para> </refsect1> <refsect1 id="sql-createstatistics-examples"> |