This depends on the type of update. If you commit the transaction
regularly, files will be re-used. On the other hand, if you commit the
transaction at the end like what the COPY command (pg_dump) does, extra WAL
files will be created as needed (even though the limit has been reached).
Regards
Robert
"Nick
Fankhauser" To: <Robert.Farrugia@go.com.mt>
<nickf@ontko. cc: <pgsql-admin@postgresql.org>
com> Subject: RE: Can't get postmaster to restart after removing WAL files
12/09/2001
16:12
Please
respond to
nickf
> You can try running pg_resetxlog (situated in the contrib directory in
the
> source). It will reset the wal files and will allow you to restart the
> postmaster.
I just did an initdb as suggested by Randy since the data was easy to
recreate, but this is good to know as a fallback for future situations!
> Try to upgrade
> to 7.1.3 since it solves some issues where long transactions take up an
> unordinated amount of space unecessary.
I was running v7.1.3 & only had two 41Mb databases running in the cluster,
which was why I was kinda' caught off guard by having 48Mb used in WAL
files.
> As regards to the space required by the WAL files this depends on the
> configuration (postgresql.conf). There is a paramter which controls the
> amount of WAL files to create (each file takes 16MB).
This helps, but I'm a bit confused- What if I'm runnning an enormous update
& I really need 4 WAL files, but I've set the limit at 3? Will an fsync be
forced so that the first file will be deleted & the space reused?
It sounds like I can limit the space used to match what I have available,
but I'm not sure if this will cause a problem if I'm too stingy on my space
allocation.
Thanks Robert & others for your help with this!
-Nick
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