Clarification Regarding Vacuum and template1
Hi :
Saw this post on BUGS mailing list :
"Olleg Samoylov" <olleg_s ( at ) mail ( dot ) ru> writes:
Opps, template1 must not be vacuumed.
Says who?
If we didn't vacuum template1 then it would be subject to
XID wraparound
problems, unless it had never been modified, which is
something vacuumdb
can't count on.
regards, tom lane
Under normal circumstances, there's no need to vacuum
template1 right? Its quite difficult to imagine XID
wraparound problems occuring in template1. I can't think
how can 4 billion transactions occur in template1 if
template1 is just used as a template in creating a new
database.
Am I missing something here?
Thank you very much,
ludwig lim
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Ludwig Isaac Lim <ludz_lim@yahoo.com> writes:
Under normal circumstances, there's no need to vacuum
template1 right?
Only if it hasn't been modified.
Its quite difficult to imagine XID
wraparound problems occuring in template1. I can't think
how can 4 billion transactions occur in template1 if
template1 is just used as a template in creating a new
database.
Am I missing something here?
Yes: the wraparound limit is for transactions cluster-wide, not per
database. If you make 1 change in template1 and then 2 billion
changes in some other databases, template1 is broken unless it's
been vacuumed meanwhile.
regards, tom lane
Yes: the wraparound limit is for transactions
cluster-wide, not per
database. If you make 1 change in template1 and then 2
billion
changes in some other databases, template1 is broken
unless it's
been vacuumed meanwhile.regards, tom lane
So in practice, should one vacuum template1 when
vacuuming other database (Assuming one doesn't use vaccumdb
script when vacuuming database)?
Will this problem occur if I vacuum all database except
template1?
Thanks for the previous quick response.
Thank you once again.
ludwig lim
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So in practice, should one vacuum template1 when
vacuuming other database (Assuming one doesn't use vaccumdb
script when vacuuming database)?
In practice, it shouldn't be a big deal to vacuum template1 once in a
while, because, since it shouldn't have much data other than
pg_catalog tables in it, it shouldn't take long to vacuum it.
If you vacuum it once a day or once a week or such, the 15 seconds
won't take much out of the life of the disk drives...
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