On 3/1/07, Joshua D. Drake <jd@xxxxxxxxxxxxxxxxx> 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 > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq > -- === The PostgreSQL Company: Command Prompt, Inc. === Sales/Support: +1.503.667.4564 || 24x7/Emergency: +1.800.492.2240 Providing the most comprehensive PostgreSQL solutions since 1997 http://www.commandprompt.com/ Donate to the PostgreSQL Project: http://www.postgresql.org/about/donate PostgreSQL Replication: http://www.commandprompt.com/products/
