Re: More Praise for 7.4RC2
От | Reece Hart |
---|---|
Тема | Re: More Praise for 7.4RC2 |
Дата | |
Msg-id | 1068753047.28850.303.camel@tallac обсуждение исходный текст |
Ответ на | Re: More Praise for 7.4RC2 ("scott.marlowe" <scott.marlowe@ihs.com>) |
Ответы |
Re: More Praise for 7.4RC2
Re: More Praise for 7.4RC2 |
Список | pgsql-general |
On Thu, 2003-11-13 at 10:09, scott.marlowe wrote:
Hmm. I didn't realize that I needed to vacuum full as well -- I thought vacuum was sufficient for performance gains, and that full reclaimed space but didn't result in significant performance gains. I have reindexed infrequently, but since that locks the table I didn't do that (or vacuum full) often. I guess I should try out pg_autovacuum, but I think that full vacuums only to prevent XID wraparound (if age>1.5B transactions), but not for compaction (is this correct?).
7.3.4, long-running db: eons
7.3.4, freshly restored: 72s
7.4RC2, freshly restored: 0.3s
Thanks everyone for feedback and setting me straight. Although the gain isn't as great as I thought, it's still very significant.
-Reece
Do you vacuum full every so often? If not, and if you've been overflowing your fsm, then your tables will just grow without shrinking. Also, index growth could be a problem.
Hmm. I didn't realize that I needed to vacuum full as well -- I thought vacuum was sufficient for performance gains, and that full reclaimed space but didn't result in significant performance gains. I have reindexed infrequently, but since that locks the table I didn't do that (or vacuum full) often. I guess I should try out pg_autovacuum, but I think that full vacuums only to prevent XID wraparound (if age>1.5B transactions), but not for compaction (is this correct?).
It turns out that I have two copies of this database around at the moment running on 7.3.4. One was a fresh restore, and that's what I used to generate the explain. However, the query was run on the older database which was vacuumed and analyzed (but not vacuum full or reindexed), and on that instance the query took a long time. On the fresh install, it takes 72s. In summary:The real test is to dump the database and reload it to give 7.3.4 a fair shake.
7.3.4, long-running db: eons
7.3.4, freshly restored: 72s
7.4RC2, freshly restored: 0.3s
Thanks everyone for feedback and setting me straight. Although the gain isn't as great as I thought, it's still very significant.
-Reece
-- Reece Hart, http://www.in-machina.com/~reece/, GPG:0x25EC91A0 |
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