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Re: Gin indexes on intarray is fast when value in array does not exists, and slow, when value exists - Mailing list pgsql-general

From Jeff Janes
Subject Re: Gin indexes on intarray is fast when value in array does not exists, and slow, when value exists
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Msg-id CAMkU=1zcRSAKZbZian2u3_eZPEHQBTr9kVBP2=jFZwX6=fCc0A@mail.gmail.com
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In response to Gin indexes on intarray is fast when value in array does not exists, and slow, when value exists  (otar shavadze <oshavadze@gmail.com>)
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On Tue, Nov 8, 2016 at 9:43 AM, otar shavadze <oshavadze@gmail.com> wrote:
I have table with 500 000 rows, I have int[] column "my_array" in this table, this array column contains minimum 1 and maximum 5 different values.

I have GIN index on my_array column:

 "CREATE INDEX idx ON table_name USING GIN(my_array gin__int_ops)"

Then I use this query: "SELECT * FROM  table_name WHERE my_array @> '{3}'::integer[]  ORDER BY id LIMIT 50"

Execution time of this query is approximately 500-1000 ms. Then if I drop gin index "idx", query works extremely fast, less than 20 ms.

Please post the information requested here: https://wiki.postgresql.org/wiki/Slow_Query_Questions

Also, can you show, 

select * from pg_stats where tablename ='table_name' and attname='my_array' \x\g\x

Cheers,

Jeff

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