On Wed, 28 Feb 2007, Tom Lane wrote:

"Joshua D. Drake" <[EMAIL PROTECTED]> writes:
Martijn van Oosterhout wrote:
Generally, rolling back a transaction doesn't reduce the amount of disk
used. Only VACUUM FULL actually shrinks relations.

Right, but what I mean was -- if we rollback because we hit quota we
could potentially cause even more maintenance to have to happen (vacuum).

It's worse than that, because VACUUM FULL will actually bloat the
indexes on the way to being able to reduce the table size (since it has
to make new index entries for rows it moves).  If the limit is strictly
enforced then a user who has reached his quota is really totally
screwed: the only easy way to get back under quota will be to completely
drop tables, ie, discard data.  VACUUM probably won't reduce the
physical table size much, and VACUUM FULL will fail, and other
approaches such as CLUSTER won't work either.

I don't know, but in my opinion, I don't see anything bad in requiring dropping the data if the quota is full. That's what usually occurs in the case of normal filesystem quota... If you don't have a space there, you cannot edit files, copy them etc... And that solution should be definitely better than the filesystem quota for the PostgreSQL user for example.

Sergey E. Koposov
Max Planck Institute for Astronomy/Cambridge Institute for Astronomy/Sternberg 
Astronomical Institute
Tel: +49-6221-528-349
Web: http://lnfm1.sai.msu.ru/~math

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