Re: Postgres seems to use indexes in the wrong order
On Tue, Jan 27, 2015 at 6:59 AM, Tim Uckun <timuckun@gmail.com> wrote:
The query seems to first use the timestamp column which results in a huge number of records and then filters out using the integer and the macaddr indices. If it was to use the integer index first it would start with a tiny number of records.
May be the record distribution of quantiles is skewed. Have you tried to set more granular statistics for your int column?
The effective_cache_size is one gig. The others are not set so therefore the default.
Ideally the effective_cache_size can be set to as much as 50-60% of your available memory. Also you need to tune your random_page_cost as per the behavior of your disk.
If these two does not work then may be you should go for setting a more granular statistics collection for your specific column-
alter table <table_name> alter column <column_Name> set statistics 1000;
analyze <table_name>;
Best Regards,
Sameer Kumar | Database Consultant
ASHNIK PTE. LTD.
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