hi, does anyone know what session level locks mean in postgresql..i've heard 
of table-level locks and row level locks but not session level
thanks
Jenny

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Fri, 08 Aug 2003 12:30:40 -0700
"Jenny -" <nat_lazy@hotmail.com>
session level locks
"Jenny -" <nat_lazy@hotmail.com> writes:
> hi, does anyone know what session level locks mean in postgresql..i've heard 
> of table-level locks and row level locks but not session level

It's a hack for VACUUM.  VACUUM needs to run two transactions to
vacuum both a table and its toast table; plus another one if it's
going to ANALYZE.  Ordinary locks would go away at transaction
commit.  Session locks are used to ensure the table doesn't disappear
till we're done vacuuming.

I doubt that session locks as currently designed are good for anything
except VACUUM.  They *do* go away on error abort --- which is exactly
what VACUUM wants, but is unlikely to be useful behavior for anything
else.

			regards, tom lane

Fri, 08 Aug 2003 15:48:50 -0400
Tom Lane <tgl@sss.pgh.pa.us>
Re: session level locks 