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I'm having a
problem with a query on our production server, but not on a laptop running a
similar postgres version with a recent backup copy of the same table.
I tried reindexing the table on the production
server, but it didn't make any difference. Other queries on the same table are
plenty fast.
This query has been slow, but never like this,
particularly during a period when there are only a couple of connections in use.
Vacuum and analyze are run nightly (and
show as such in pg_stat_user_tables) in addition to autovacuum during
the day. Here are my autovacuum settings, but when I checked
last_autovacuum & last_autoanalyze in pg_stat_user_tables those fields
were blank.
autovacuum =
on
log_autovacuum_min_duration = 10 autovacuum_max_workers = 3 autovacuum_naptime = 1min autovacuum_vacuum_threshold = 50 autovacuum_analyze_threshold = 50 autovacuum_vacuum_scale_factor = 0.2 autovacuum_analyze_scale_factor = 0.1 autovacuum_freeze_max_age = 200000000 autovacuum_vacuum_cost_delay = 10ms (changed earlier today from 1000ms) autovacuum_vacuum_cost_limit = -1 wal_level = minimal
wal_buffers = 16MB
The only recent change was moving the 3 databases
we have from multiple raid 1 drives with tablespaces spread all over to one
large raid10 with indexes and data in pg_default. WAL for this table was moved
as well.
Does anyone have any suggestions on where to look
for the problem?
clientlog table info:
Size: 1.94G
Column
|
Type |
Modifiers
----------+-----------------------------+----------- pid0 | integer | not null rid | integer | not null verb | character varying(32) | not null noun | character varying(32) | not null detail | text | path | character varying(256) | not null ts | timestamp without time zone | applies2 | integer | toname | character varying(128) | byname | character varying(128) | Indexes: "clientlog_applies2" btree (applies2) "clientlog_pid0_key" btree (pid0) "clientlog_rid_key" btree (rid) "clientlog_ts" btree (ts) The query, hardware info, and links to both
plans:
explain analyze select max(ts) as ts from
clientlog where applies2=256;
Production server:
- 4 dual-core AMD Opteron 2212 processors,
2010.485 MHz
- 64GB RAM - 464GB RAID10 drive - Linux 2.6.18-164.el5 #1 SMP Thu Sep 3 03:28:30 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux PostgreSQL 9.0.4 on
x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.1.2 20080704 (Red Hat
4.1.2-46), 64-bit
From laptop running Linux 2.6.34.9-69.fc13.868
with 3G ram against a copy of the same table:
PostgreSQL 9.0.2 on i686-pc-linux-gnu, compiled
by GCC gcc (GCC) 4.4.4 20100630 (Red Hat 4.4.4-10), 32-bit
Thank you,
Midge
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