On 31.05.2013 00:06, Bruce Momjian wrote:
On Thu, May 30, 2013 at 04:33:50PM +0300, Heikki Linnakangas wrote:
This would also be the first step in allowing the clog to grow
larger than 2 billion transactions, eliminating the need for
anti-wraparound freezing altogether. You'd still want to truncate
the clog eventually, but it would be nice to not be pressed against
the wall with "run vacuum freeze now, or the system will shut down".
Keep in mind that autovacuum_freeze_max_age is 200M to allow faster clog
truncation. Does this help that?
No. If you want to keep autovacuum_freeze_max_age set at less than 2
billion, you don't need support for more than 2 billion transactions.
But for those who would like to set autovacuum_freeze_max_age higher
than 2B, it would be nice to allow it.
Actually, even with autovacuum_freeze_max_age = 200 M, it would be nice
to not have the hard stop at 2 billion, in case autovacuum falls behind
really badly. With autovacuum_freeze_max_age = 200M, there's a lot of
safety margin, but with 1000M or so, not so much.
- Heikki
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