cannot disable hashSetOp

Lists: pgsql-hackers
From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: cannot disable hashSetOp
Date: 2012-11-20 07:29:25
Message-ID: CAFj8pRBTtk-X5FbECMnLO4p5CN-uLdwdSb9f2p41zcbcoMeA2g@mail.gmail.com
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Lists: pgsql-hackers

hello

I looked on issue with consuming memory by query

HashSetOp Except (cost=0.00..297100.69 rows=594044 width=30)
-> Append (cost=0.00..234950.32 rows=8286716 width=30)
-> Subquery Scan on "*SELECT* 1" (cost=0.00..168074.62
rows=5940431 width=29)
-> Seq Scan on ac (cost=0.00..108670.31 rows=5940431 width=29)
-> Subquery Scan on "*SELECT* 2" (cost=0.00..66875.70
rows=2346285 width=32)
-> Seq Scan on artist_credit (cost=0.00..43412.85
rows=2346285 width=32)

I was surprised, because I didn't find any way how to disable hashing.

Is there some way?

Pavel