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Re: Problem with TOAST tables when removing TOASTable column

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Wojciech Strzałka <wstrzalka(at)gmail(dot)com>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: Problem with TOAST tables when removing TOASTable column
Date: 2008-05-14 16:22:29
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Lists: pgsql-bugs
=?iso-8859-2?Q?Wojciech_Strza=B3ka?= <wstrzalka(at)gmail(dot)com> writes:
>> To make that happen would require (at least) a full table scan.  I think
>> most people are more interested in DROP COLUMN being a cheap operation
>> than in having the space be reclaimed quickly.

>> For a comparison point: large field values that don't happen to get
>> toasted don't vanish immediately, either.

> I agree DROP COLUMN should be cheap and I don't really expect it to happend immediately,
> but shouldn't VACUUM FULL clean it up?

No, changing the content of existing tuples is outside VACUUM's purview.

FWIW, I believe that a CLUSTER would clean it up, and would likely be
faster than a VACUUM FULL anyway.

			regards, tom lane

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