From: Tom Lane <tgl@sss.pgh.pa.us>
To: James Pang (chaolpan) <chaolpan@cisco.com>
Cc: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: huge memory of Postgresql backend process
Date: Thu, 08 Sep 2022 09:47:57 -0400
Message-ID: <3950547.1662644877@sss.pgh.pa.us> (raw)
In-Reply-To: <PH0PR11MB51911F681F37F55A92DA4C01D6409@PH0PR11MB5191.namprd11.prod.outlook.com>
References: <PH0PR11MB51911F681F37F55A92DA4C01D6409@PH0PR11MB5191.namprd11.prod.outlook.com>
"James Pang (chaolpan)" <chaolpan@cisco.com> writes:
> We just switch from Oracle to PGV13, all of these tables got partition (256 HASH partition) , when UPDATE/DELETE ... WHERE . The memory increase verify quickly until >130M. not too much data in these tables. When we switch to PGV14.5 , test again, still see similar memory consumption issue.
I see no particular reason to think this is a bug. If you have a
lot of partitions, there is going to be a lot of metadata for them.
Moreover, HASH partitioning is effectively incapable of being
pruned, so that every query is going to touch every partition.
(IMO, hash partitioning is basically never a good idea.)
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, chaolpan@cisco.com, pgsql-bugs@lists.postgresql.org
Subject: Re: huge memory of Postgresql backend process
In-Reply-To: <3950547.1662644877@sss.pgh.pa.us>
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