patch: optimize information_schema.constraint_column_usage

From: Alexey Bashtanov <bashtanov(at)imap(dot)cc>
To: pgsql-hackers(at)postgresql(dot)org
Subject: patch: optimize information_schema.constraint_column_usage
Date: 2017-02-02 13:27:51
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Hello hackers,

The view information_schema.constraint_column_usage becomes slow when
the number of columns and constraints raise to substantial values.
This is because of a join condition that allows only join filter to
enforce. The patch is to optimize it.
See many_constraints.sql file attached for a performance test: create
3000 tables with 10 columns and a PK each and select * from the view.
The last statement works for 22 seconds on master branch, 34
milliseconds optimized on my laptop.

Best Regards,
Alexey Bashtanov

Attachment Content-Type Size
many-constraints.sql application/sql 811 bytes
constraint_column_usage.1.patch text/x-patch 880 bytes


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