In an attempt to review a machine for optimal OLTP configuration of
Postgres box, turned WAL debug to 1 and ran under load for 24 hours. That
resulted in a 67+ meg postmaster logfile. But I'm not sure how to
interpret the results. Without going through the 700,000+ lines, the basic
info looks like this:
INSERT @ 7/2838581988: prev 7/2838573716; xprev 7/2838573716; xid 38868268;
bkpb
1: Btree - insert: node 18720/20077; tid 219/75
INSERT @ 7/2838590260: prev 7/2838581988; xprev 7/2838581988; xid 38868268;
bkpb
1: Btree - insert: node 18720/11144803; tid 201/94
INSERT @ 7/2838598532: prev 7/2838590260; xprev 7/2838590260; xid 38868268:
Heap
- update: node 18720/19299; tid 431/8; new 431/21
XLogFlush: rqst 7/2838540592; wrt 7/2838593536; flsh 7/2838524040
XLogFlush: rqst 7/2838557172; wrt 7/2838598740; flsh 7/2838598740
XLogFlush: rqst 7/2838565444; wrt 7/2838598740; flsh 7/2838598740
XLogFlush: rqst 7/2838573716; wrt 7/2838598740; flsh 7/2838598740
I know in general that I'm looking at inserts into the log buffers and
flushes of the buffers to permanent storage. I also know that a bad
situation is one where all buffers fill up and an insert must wait for a
flush. How can I examine this output to know if that is happening? Also,
is there anything else I can look for within this data to tell me if I have
a configuration problem that could use some tuning?
FYI:
version
-------------------------------------------------------------
PostgreSQL 7.1.2 on i686-pc-linux-gnu, compiled by GCC 2.96
Thanks for any help that can be provided.
Marc Mitchell - Senior Application Architect
Enterprise Information Solutions, Inc.
Downers Grove, IL 60515
marcm@eisolution.com