[ADMIN] When vaccuum full should be performed with postgresql-8.1 and autovaccuum?

[Arnau]

Hi all,

  I'm migrating our DDBB from postgresql 7.4 to postgresql 8.1. In 
postgreql 7.4 we don't have autovaccum running. So, every night before 
doing the daily backup we do a vaccuumdb -f -z for each DB. My doubt 
is, the autovaccuum  with the version 8.1 is started by default and I 
don't know how often I should perform the vaccuumdb -f -z or now it's 
not necessary to do it at all.


Thank you very much
--
Arnau

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Re: [ADMIN] When vaccuum full should be performed with postgresql-8.1

[Matthew T. O'Connor]

Arnau wrote:
I'm migrating our DDBB from postgresql 7.4 to postgresql 8.1. In 
postgreql 7.4 we don't have autovaccum running. So, every night before 
doing the daily backup we do a vaccuumdb -f -z for each DB. My doubt 
is, the autovaccuum  with the version 8.1 is started by default and I 
don't know how often I should perform the vaccuumdb -f -z or now 
it's not necessary to do it at all. 
First off, you should never really need vacuumdb -f, in fact autovacuum 
doesn't do full vacuums, rather it only does the standard vacuum.


In theory autovacuum should perform all the vacuuming that is needed, 
however, in practice this isn't always the case.  First the most people 
find the default thresholds for autovacuum in 8.1 are too conservative 
and second it can be a bit hard to monitor what autovacuum is doing.  
Both of these issues are improved in 8.2.  In summary, try it and see.



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