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* AW: No result when selecting attstattarget from pg_attribute
@ 2019-11-28 15:14 William Sescu (Suva) <william.sescu@suva.ch>
0 siblings, 2 replies; 3+ messages in thread
From: William Sescu (Suva) @ 2019-11-28 15:14 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: pgsql-admin
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@sss.pgh.pa.us>
Gesendet: Donnerstag, 28. November 2019 15:54
An: Sescu William (SW0) <william.sescu@suva.ch>
Cc: pgsql-admin@postgresql.org
Betreff: Re: No result when selecting attstattarget from pg_attribute
"William Sescu (Suva)" <william.sescu@suva.ch> 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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^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: AW: No result when selecting attstattarget from pg_attribute
@ 2019-11-28 15:23 Laurenz Albe <laurenz.albe@cybertec.at>
parent: William Sescu (Suva) <william.sescu@suva.ch>
1 sibling, 0 replies; 3+ messages in thread
From: Laurenz Albe @ 2019-11-28 15:23 UTC (permalink / raw)
To: William Sescu (Suva) <william.sescu@suva.ch>; Tom Lane <tgl@sss.pgh.pa.us>; +Cc: pgsql-admin
On Thu, 2019-11-28 at 15:14 +0000, William Sescu (Suva) wrote:
> 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;
You are worrying without need.
While the actual statistics won't be upgraded, the *definition* for
extended statistics will be. So your CREATE STATISTICS won't vanish
during an upgrade.
You'll have to ANALYZE after upgrading so that PostgreSQL collects the
extended statistics.
Extended statistics are stored in the "pg_statistic_ext" catalog.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: AW: No result when selecting attstattarget from pg_attribute
@ 2019-11-28 15:29 Tom Lane <tgl@sss.pgh.pa.us>
parent: William Sescu (Suva) <william.sescu@suva.ch>
1 sibling, 0 replies; 3+ messages in thread
From: Tom Lane @ 2019-11-28 15:29 UTC (permalink / raw)
To: William Sescu (Suva) <william.sescu@suva.ch>; +Cc: pgsql-admin
"William Sescu (Suva)" <william.sescu@suva.ch> writes:
> 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?
You are apparently confusing the *definition* of a statistics object
with the *content*. pg_upgrade will certainly transfer the former.
Run ANALYZE to re-fill the latter.
regards, tom lane
^ permalink raw reply [nested|flat] 3+ messages in thread
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2019-11-28 15:14 AW: No result when selecting attstattarget from pg_attribute William Sescu (Suva) <william.sescu@suva.ch>
2019-11-28 15:23 ` Laurenz Albe <laurenz.albe@cybertec.at>
2019-11-28 15:29 ` Tom Lane <tgl@sss.pgh.pa.us>
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