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Commite3a58c8

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Optimize query for information_schema.constraint_column_usage
The way the old query was written prevented some join optimizationsbecause the join conditions were hidden inside a CASE expression. Witha large number of constraints, the query became unreasonably slow. Thenew query performs much better.From: Alexey Bashtanov <bashtanov@imap.cc>Reviewed-by: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
1 parent68f3dbc commite3a58c8

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‎src/backend/catalog/information_schema.sql

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -801,8 +801,8 @@ CREATE VIEW constraint_column_usage AS
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WHEREnr.oid=r.relnamespace
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ANDr.oid=a.attrelid
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ANDnc.oid=c.connamespace
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AND(CASE WHENc.contype='f' THENr.oid=c.confrelidANDa.attnum= ANY (c.confkey)
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ELSEr.oid=c.conrelidANDa.attnum= ANY (c.conkey) END)
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ANDr.oid= CASEc.contypeWHEN'f' THENc.confrelidELSEc.conrelid END
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ANDa.attnum= ANY (CASEc.contype WHEN'f' THENc.confkey ELSEc.conkey END)
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AND NOTa.attisdropped
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ANDc.contypeIN ('p','u','f')
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ANDr.relkindIN ('r','P')

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