Thank you Tom for clarification. However, in regards of pg_upgrade, which does not transfer statistics, how do I know
how to create the "CREATE STATISTICS" on the new PostgreSQL version?
e.g. Developers created a whole bunch of "CREATE STATISTICS" on all kind of tables, which ends up in pg_statistic_ext view.
select * from pg_statistic_ext;
stxrelid | stxname | stxnamespace | stxowner | stxkeys | stxkind | stxndistinct | stxdependencies
----------+---------+--------------+----------+---------+---------+--------------+----------------------
35600 | s1 | 16579 | 16569 | 1 2 | {f} | | {"1 => 2": 1.000000}
Is there any way how I can translate the view entries into into a SQL again?
CREATE STATISTICS s1 (dependencies) ON a, b FROM t1;
-----Ursprüngliche Nachricht-----
Von: Tom Lane <tgl@xxxxxxxxxxxxx>
Gesendet: Donnerstag, 28. November 2019 15:54
An: Sescu William (SW0) <william.sescu@xxxxxxx>
Cc: pgsql-admin@xxxxxxxxxxxxxx
Betreff: Re: No result when selecting attstattarget from pg_attribute
"William Sescu (Suva)" <william.sescu@xxxxxxx> writes:
> I was following the create statistics example from the doc
> https://www.postgresql.org/docs/11/sql-createstatistics.html
> and wondered why I don't see any results when selecting attstattarget from pg_attribute.
attstattarget has nothing to do with extended statistics.
It's for recording "ALTER TABLE ... SET STATISTICS n"
commands, which just control the granularity of the regular (pg_statistic) statistics.
Look into pg_statistic_ext to see the effects of CREATE STATISTICS.
regards, tom lane
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