From: David Wall <d.wall@computer.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-general@postgresql.org
Subject: Re: Vacuum analyze in 7.1.1
Date: Wed, 13 Jun 2001 15:55:21 -0700
Message-ID: <006501c0f45b$eca1c580$5a2b7ad8@expertrade.com> (raw)
References: <00c401c0f43b$a5423000$5a2b7ad8@expertrade.com>
<3101.992468005@sss.pgh.pa.us>
> AFAIK that's always been true, but some of the documentation has been
> confused about it :-(. If you can find anything in the 7.1 docs that
> sounds like VACUUM ANALYZE doesn't include VACUUM, please point it out.
Thanks. The documentation doesn't say that VACUUM ANALYZE doesn't do a
regular VACUUM as well, but it does say:
"VACUUM serves two purposes in Postgres as both a means to reclaim storage
and also a means to collect information for the optimizer." So, I know it
does two things. It then says:
"VACUUM ANALYZE collects statistics representing the dispersion of the data
in each column. This information is valuable when several query execution
paths are possible." This is also clear to me, but it left open the
possibility that this is ALL that ANALYZE does, and does not clean out
records and update the stats as VACUUM does. The docs say that VACUUM:
"VACUUM opens every table in the database, cleans out records from rolled
back transactions, and updates statistics in the system catalogs. The
statistics maintained include the number of tuples and number of pages
stored in all tables."
Isn't also true that VACUUM cleans out deleted and updated rows for
committed transactions? And for those who use large objects, I understand
that vacuum now cleans those up when they are deleted as well (no need for
vacuumlo anymore). Perhaps it would be clear to just add words to that
affect, and to mention that VACUUM ANALYZE does a VACUUM plus it collects
statistics...
David
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To: pgsql-interfaces@postgresql.org
Cc: d.wall@computer.org, tgl@sss.pgh.pa.us, pgsql-general@postgresql.org
Subject: Re: Vacuum analyze in 7.1.1
In-Reply-To: <006501c0f45b$eca1c580$5a2b7ad8@expertrade.com>
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