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DANTE Alexandra *nix forums beginner
Joined: 07 Jul 2006
Posts: 9
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Posted: Wed Jul 19, 2006 1:03 pm Post subject:
VACUUM and index
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Hello List,
Sorry to send an other e-mail on this subject but it is become a little
bit vague for me.
Imagine you have a database on which a lot of transactions are done
daily : the tables will contain a lot of dead tuples and the B-tree
index too.
If I do a VACUUM on this database, will the B-tree index be scanned,
space reclaimed and made available for re-use ?
Does this action only do by a VACUUM FULL ?
Or is it necessary to do a REINDEX on the index to retrieve a
well-balanced tree ?
Thank you for your help.
Regards,
Alexandra DANTE
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Martijn van Oosterhout *nix forums Guru
Joined: 02 Mar 2005
Posts: 674
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Posted: Wed Jul 19, 2006 1:13 pm Post subject:
Re: VACUUM and index
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On Wed, Jul 19, 2006 at 03:03:43PM +0200, DANTE Alexandra wrote:
| Quote: | Imagine you have a database on which a lot of transactions are done
daily : the tables will contain a lot of dead tuples and the B-tree
index too.
If I do a VACUUM on this database, will the B-tree index be scanned,
space reclaimed and made available for re-use ?
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Old versions didn't, but recent versions do.
| Quote: | Does this action only do by a VACUUM FULL ?
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Also by VACUUM FULL, but plain VACIIM is enough.
| Quote: | Or is it necessary to do a REINDEX on the index to retrieve a
well-balanced tree ?
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There are always corner case situations. In older versions a REINDEX
helped balance the tree but recent versions are much better.
Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate. |
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DANTE Alexandra *nix forums beginner
Joined: 07 Jul 2006
Posts: 9
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Posted: Wed Jul 19, 2006 1:23 pm Post subject:
Re: VACUUM and index
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Thank you Martijn for your answer !
I use the 8.1.3 release of PostgreSQL.
Will it be sensible to launch an ANALYZE after the VACUUM to update
statistics ?
Regards,
Alexandra
Martijn van Oosterhout wrote:
| Quote: | On Wed, Jul 19, 2006 at 03:03:43PM +0200, DANTE Alexandra wrote:
Imagine you have a database on which a lot of transactions are done
daily : the tables will contain a lot of dead tuples and the B-tree
index too.
If I do a VACUUM on this database, will the B-tree index be scanned,
space reclaimed and made available for re-use ?
Old versions didn't, but recent versions do.
Does this action only do by a VACUUM FULL ?
Also by VACUUM FULL, but plain VACIIM is enough.
Or is it necessary to do a REINDEX on the index to retrieve a
well-balanced tree ?
There are always corner case situations. In older versions a REINDEX
helped balance the tree but recent versions are much better.
Have a nice day,
|
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Martijn van Oosterhout *nix forums Guru
Joined: 02 Mar 2005
Posts: 674
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Posted: Wed Jul 19, 2006 1:28 pm Post subject:
Re: VACUUM and index
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On Wed, Jul 19, 2006 at 03:23:08PM +0200, DANTE Alexandra wrote:
| Quote: | Thank you Martijn for your answer !
I use the 8.1.3 release of PostgreSQL.
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You'll be fine...
| Quote: | Will it be sensible to launch an ANALYZE after the VACUUM to update
statistics ?
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Or do both at the same time (VACUUM ANALYZE).
Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate. |
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