We're still considering this architecture - so I don't have any plans. My question is, does the ANALYZE command, which is only executed on the master, mean that the statistics / plans that are used on the master are ALSO used on the slaves? OR .... does the slave create it's own plan?
I would anticipate very different plans between the two machines, and different postgresql.conf settings as well. I would *want* different query plans between the two. Is that possible? On Sun, Nov 9, 2014 at 8:50 PM, Tatsuo Ishii <is...@postgresql.org> wrote: > > Hi all! > > > > We're working on our architecture for our next set of systems, and we > > normally have a simple master/slave with wal shipping and hot_standby set > > up, with pgpool sitting in front of both to do load balancing. > > > > However, one piece I'm very confused about is the query plans on the > slave > > server. > > > > Let's pretend we have a master server with: > > (2) E5-2660 CPU's > > (4) S3700 400GB SSD's > > 256GB of RAM > > > > And multiple slave servers that looks like: > > (1) E3-1290 CPU's > > (2) Intel 520 SSD's > > 32GB of RAM > > > > There's a significant difference between the master and slaves. > > Can you show us the explain analyze result on both master and slave? > > > Does the ANALYZE command run on each system, and work differently on each > > system, or would the slave servers use the query plans from the master > > machine? > > ANALYZE can only be executed on master. Slave creates its own > plan. However since statistics should be same as master, I guess if > you get different plan, then postgresql.conf maybe different among > master and slave. > > Best regards, > -- > Tatsuo Ishii > SRA OSS, Inc. Japan > English: http://www.sraoss.co.jp/index_en.php > Japanese:http://www.sraoss.co.jp >
