On 3/1/07, Joshua D. Drake <[EMAIL PROTECTED]> wrote:
Alex Deucher wrote:
> Hello,
>
> I have noticed a strange performance regression and I'm at a loss as
> to what's happening. We have a fairly large database (~16 GB). The
> original postgres 7.4 was running on a sun v880 with 4 CPUs and 8 GB
> of ram running Solaris on local scsi discs. The new server is a sun
> Opteron box with 4 cores, 8 GB of ram running postgres 8.1.4 on Linux
> (AMD64) on a 4 Gbps FC SAN volume. When we created the new database
> it was created from scratch rather than copying over the old one,
> however the table structure is almost identical (UTF8 on the new one
> vs. C on the old). The problem is queries are ~10x slower on the new
> hardware. I read several places that the SAN might be to blame, but
> testing with bonnie and dd indicates that the SAN is actually almost
> twice as fast as the scsi discs in the old sun server. I've tried
> adjusting just about every option in the postgres config file, but
> performance remains the same. Any ideas?
Vacuum? Analayze? default_statistics_target? How many shared_buffers?
effective_cache_size? work_mem?
I'm running the autovacuum process on the 8.1 server. vacuuming on
the old server was done manually.
default_statistics_target and effective_cache_size are set to the the
defaults on both.
postgres 7.4 server:
# - Memory -
shared_buffers = 82000 # 1000 min 16, at least
max_connections*2, 8KB each
sort_mem = 8000 # 1024 min 64, size in KB
vacuum_mem = 32000 # 8192 min 1024, size in KB
# - Free Space Map -
#max_fsm_pages = 20000 # min max_fsm_relations*16, 6 bytes each
#max_fsm_relations = 1000 # min 100, ~50 bytes each
# - Kernel Resource Usage -
#max_files_per_process = 1000 # min 25
postgres 8.1 server:
# - Memory -
shared_buffers = 100000 # min 16 or max_connections*2, 8KB each
temp_buffers = 2000 #1000 # min 100, 8KB each
max_prepared_transactions = 100 #5 # can be 0 or more
# note: increasing max_prepared_transactions costs ~600 bytes of shared memory
# per transaction slot, plus lock space (see max_locks_per_transaction).
work_mem = 10000 #1024 # min 64, size in KB
maintenance_work_mem = 524288 #16384 # min 1024, size in KB
#max_stack_depth = 2048 # min 100, size in KB
I've also tried using the same settings from the old server on the new
one; same performance issues.
Thanks,
Alex
Sincerely,
Joshua D. Drake
>
> Thanks,
>
> Alex
>
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