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From: ma lz <[email protected]>
To: [email protected] <[email protected]>
Subject: Why not do distinct before SetOp
Date: Mon, 4 Nov 2024 09:52:12 +0000
Message-ID: <TYCPR01MB63514B9C70EF2A80F0D43394F2512@TYCPR01MB6351.jpnprd01.prod.outlook.com> (raw)

some sql like ' select a from t1 intersect select a from t1 '

if t1 has large number rows but has few distinct rows

select distinct a from t1 intersect select distinct a from t1;    — this is faster than origin sql

can postgres do this optimize during plan-queries?

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