Re: BUG #5946: Long exclusive lock taken by vacuum (not full)

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Greg Stark <gsstark@mit.edu>, Alvaro Herrera <alvherre@commandprompt.com>, Christopher Browne <cbbrowne@gmail.com>, Maxim Boguk <maxim.boguk@gmail.com>, pgsql-bugs <pgsql-bugs@postgresql.org>
Date: 2011-03-28T04:29:12Z
Lists: pgsql-bugs
Robert Haas <robertmhaas@gmail.com> writes:
> I think we've had a number of pieces of evidence that suggest that
> extending 8kB at a time is too costly, but I agree with Greg that the
> idea of extending an arbitrarily large table by 10% at a time is
> pretty frightening - that could involve allocating a gigantic amount
> of space on a big table.  I would be inclined to do something like
> extend by 10% of table or 1MB, whichever is smaller.

Sure, something like that sounds sane, though the precise numbers
need some validation.

> ... And a 1MB extension is probably also small enough
> that we can do it in the foreground without too much of a hiccup.

Less than convinced about this.

			regards, tom lane