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Mention statistics objects in maintenance.sgml

author Tomas Vondra <tomas.vondra@postgresql.org>

Fri, 7 May 2021 12:02:22 +0000 (14:02 +0200)

committer Tomas Vondra <tomas.vondra@postgresql.org>

Fri, 7 May 2021 12:40:41 +0000 (14:40 +0200)

The docs mentioned expression indexes as a way to improve selectivity
estimates for functions, but we have a second option to improve that by
creating extended statistics. So mention that too.

Reported-by: Justin Pryzby
Discussion: https://postgr.es/m/20210505210947.GA27406%40telsasoft.com

doc/src/sgml/maintenance.sgml patch | blob | blame | history

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml

index ee6113926ac8c5756aa9a595a6acf72634d94eeb..de7fd75e1c609e8043a6f87bbd105168be6bafe7 100644 (file)

--- a/doc/src/sgml/maintenance.sgml

+++ b/doc/src/sgml/maintenance.sgml

@@ -330,7 +330,8 @@

<para>

Also, by default there is limited information available about

- the selectivity of functions. However, if you create an expression

+ the selectivity of functions. However, if you create a statistics

+ object or an expression

index that uses a function call, useful statistics will be

gathered about the function, which can greatly improve query

plans that use the expression index.

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