Thread: Streaming replication performance
Hi all, I'm testing Streamin replication with one hot standby node and I'm experiencing high delay of hot standby node. When I reach aprox. 50 transactions per second where every transaction includes only simple "UPDATE status SET number = number + 1 WHERE name = 'iterations'", the standby server falls behind master and the delay is several minutes. In comparison, Slony1 have no issues with the same test and its delay is only several seconds. Am I missing some configuration that affects speed of streaming replicaiton? Both servers are connected using 1Gb network, CPU usage of both servers is low, disk latency is not issue. master server postgresql.conf ----- wal_level = 'hot_standby' vacuum_defer_cleanup_age = 10000 checkpoint_segments = 8 checkpoint_timeout = 30s archive_mode = off max_wal_senders = 3 wal_sender_delay = 10ms wal_keep_segments = 128 ----- standby server postgresql.conf ----- hot_standby = on max_standby_streaming_delay = 30s ----- standby server recovery.conf ----- standby_mode = 'on' primary_conninfo = 'host=master port=5432 user=replication2 password=password' trigger_file = '/var/lib/postgresql/9.0/main/replica_trigger' ----- Thank you for any advice Antonin Faltynek
On Thu, Aug 11, 2011 at 9:46 AM, Antonin Faltynek <pin007@gmail.com> wrote: > Hi all, > > I'm testing Streamin replication with one hot standby node and I'm > experiencing high delay of hot standby node. > > When I reach aprox. 50 transactions per second where every transaction > includes only simple "UPDATE status SET number = number + 1 WHERE name = > 'iterations'", the standby server falls behind master and the delay is several > minutes. In comparison, Slony1 have no issues with the same test and its delay > is only several seconds. > > Am I missing some configuration that affects speed of streaming replicaiton? hm -- how are you determining the standby is behind? are you running any other queries on the standby? merlin
Dne Pá 12. srpna 2011 18:47:24 Merlin Moncure napsal(a): > On Thu, Aug 11, 2011 at 9:46 AM, Antonin Faltynek <pin007@gmail.com> wrote: > > Hi all, > > > > I'm testing Streamin replication with one hot standby node and I'm > > experiencing high delay of hot standby node. > > > > When I reach aprox. 50 transactions per second where every transaction > > includes only simple "UPDATE status SET number = number + 1 WHERE name = > > 'iterations'", the standby server falls behind master and the delay is > > several minutes. In comparison, Slony1 have no issues with the same test > > and its delay is only several seconds. > > > > Am I missing some configuration that affects speed of streaming > > replicaiton? > > hm -- how are you determining the standby is behind? are you running > any other queries on the standby? > > merlin Simply, during test I'm generating series of numbers that I'm periodicaly checking on both master and stand by server. Also I'm measuring several server metrics, like CPU usage, disk usage, network bandwidth. When testing streaming replication network usage does not get over 1Mbps and catching master takes several tens of minutes, while during test of WAL file shipping, network usage get to 3-5Mpbs and stand by server does not fall behind master more than several seconds. There is no other traffic on stand by server, only periodical check of test table (SELECT * FROM status) every 2s. Extension of this check interval does not affect behavior of streaming replication. Tonda