What parameters to tweak for a text-based PG restore?
Every night we dump and restore a 200 GB database using:
# Production, PG 9:
pg_dump DATNAME | some-irrelevant-pipe
# QA, PG 8.3:
some-irrelevant-pipe | psql -d DATNAME
I had to go for text-based backups in order to restore a dump from 9 on 8.3.
The restore is painfully and unreasonably slow. I noticed my log is full of these:
2011-05-22 08:02:47 CDT LOG: checkpoints are occurring too frequently (9 seconds apart)
2011-05-22 08:02:47 CDT HINT: Consider increasing the configuration parameter "checkpoint_segments".
2011-05-22 08:02:54 CDT LOG: checkpoints are occurring too frequently (7 seconds apart)
2011-05-22 08:02:54 CDT HINT: Consider i开发者_运维百科ncreasing the configuration parameter "checkpoint_segments".
My question is: Is it possible that the setting of checkpoint_segments
is the bottleneck? What other parameters can I tweak to speed up the process?
That machine has 4 GB RAM. Other possibly relevant settings in postgresql.conf are:
shared_buffers = 1000MB
work_mem = 200MB
maintenance_work_mem = 200MB
effective_cache_size = 2000MB
# fsync and checkpoint settings are default
Did you read this ? See specially sec 14.4.9
For the purposes of restoring a database, change:
# I don't think PostgreSQL 8.3 supports synchronous_commit
synchronous_commit = off
# only change fsync = off if your version of PG is too old to support synchronous_commit. If you do support synchronous_commit, don't ever change fsync to anything but on. Ever.
#fsync = off
checkpoint_segments = 25
Regarding checkpoint_segments, set that value to the size of your disk controller's write buffer. 25 = 400MB
Also, make sure your psql
is loading everything in a single transaction:
some-irrelevant-pipe | psql -1 -d DATNAME
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