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We also have in our postgresql.conf file
autovaccum = on default_statistics_target = 100 Do you recommend any changes? This partitioned table doti_sensor_report contains in total approximately 15 billion rows, autovaccum current has three processes that are running continuously on the box and specifically targeting this table to keep up. What does the upgrade to 9.3.5 buy us in terms of performance improvements? thanks Victor Freddie From: Victor Yegorov [vyegorov@xxxxxxxxx]
Sent: Friday, September 26, 2014 4:25 PM To: Burgess, Freddie Subject: Re: Very slow postgreSQL 9.3.4 query 2014-09-26 23:07 GMT+03:00 Burgess, Freddie
<FBurgess@xxxxxxxxxxxxxxx>:
There's autovacuum that does the same job for you, I hope you have it enabled on your upgraded DB. If not, then once-a-month stats is definitely not enough.
I recommend you to look into autovacuum instead of using cron and tune per-table autovacuum settings:
Default parameters will cause autovacuum to process the table if 10% (analyze) or 20% (vacuum) of the table had changed. The bigger the table,
the longer it'll take to reach the threshold. Try lowering scale factors on a per-table basis, like:
ALTER TABLE doti_sensor_report_y2014m09 SET (autovacuum_analyze_scale_factor=0.02, autovacuum_vacuum_scale_factor=0.05);
Also, given your tables are quite big, I would recommend to increase statistics targets for commonly used columns, like:
ALTER TABLE doti_sensor_report_y2014m09 ALTER node_date_time SET STATISTICS 1000;
Have a look at the docs on these topics and pick they way that suits you most.
P.S. Consider upgrading to 9.3.5 also, it is a minor one: only restart is required.
Victor Y. Yegorov |
