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Re: VACUUM FULL changes the order of rows in a table?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Douglas Trainor <trainor(at)uic(dot)edu>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: VACUUM FULL changes the order of rows in a table?
Date: 2002-07-24 07:42:45
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-bugs
Douglas Trainor <trainor(at)uic(dot)edu> writes:
> WARNING:  Not sure if what I am about to describe is a bug.

As Scott comments, it isn't.  Under *no* circumstances does Postgres
guarantee anything about the physical order of rows in a table.
This is entirely in accordance with the SQL spec --- row ordering is
not considered significant at all in the computational model.  It's
worth noting that ORDER BY is treated by the spec as a mere output
decoration issue; you cannot ORDER the result of a sub-select, only
the final results being sent to the client.  Fundamentally SQL does
not think row order is a valid consideration at all.

			regards, tom lane

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