From: Tom Lane <tgl@sss.pgh.pa.us>
To: Murthy Nunna <mnunna@fnal.gov>
Cc: pgsql-admin@postgresql.org <pgsql-admin@postgresql.org>
Subject: Re: Query Performance after pg_restore
Date: Sun, 24 Dec 2023 11:12:15 -0500
Message-ID: <1615174.1703434335@sss.pgh.pa.us> (raw)
In-Reply-To: <DM8PR09MB66777254DC04045815B09196B89AA@DM8PR09MB6677.namprd09.prod.outlook.com>
References: <DM8PR09MB66777254DC04045815B09196B89AA@DM8PR09MB6677.namprd09.prod.outlook.com>
Murthy Nunna <mnunna@fnal.gov> writes:
> I did pg_dump of a ~20TB database followed by pg_restore. I find simple queries like select count(*) running slow. I did a select count(*) on all tables before pg_dump which took ~4 hours. After pg_restore, same thing took 32 hours.
My bet is that that was setting commit hint bits, and hence incurring
a lot of writes. If the data is reasonably stable that's a one-time
expense.
regards, tom lane
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To: pgsql-admin@postgresql.org
Cc: tgl@sss.pgh.pa.us, mnunna@fnal.gov
Subject: Re: Query Performance after pg_restore
In-Reply-To: <1615174.1703434335@sss.pgh.pa.us>
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