From: Simon Riggs <simon@2ndQuadrant.com>
To: Tom Lane <tgl@postgresql.org>
Cc: pgsql-hackers@postgresql.org
Subject: Re: [COMMITTERS] pgsql: If we expect a hash join to be performed in multiple batches,
Date: Thu, 02 Apr 2009 18:11:23 +0100
Message-ID: <1238692283.5444.123.camel@ebony.2ndQuadrant> (raw)
In-Reply-To: <20090326171535.6B9BF754ADE@cvs.postgresql.org>
References: <20090326171535.6B9BF754ADE@cvs.postgresql.org>
On Thu, 2009-03-26 at 17:15 +0000, Tom Lane wrote:
> Log Message:
> -----------
> If we expect a hash join to be performed in multiple batches, suppress
> "physical tlist" optimization on the outer relation (ie, force a projection
> step to occur in its scan). This avoids storing useless column values when
> the outer relation's tuples are written to temporary batch files.
Can we add "batches=N" to the EXPLAIN output for Hash and/or Hash Join?
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support
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To: pgsql-committers@postgresql.org
Cc: simon@2ndQuadrant.com, tgl@postgresql.org, pgsql-hackers@postgresql.org
Subject: Re: [COMMITTERS] pgsql: If we expect a hash join to be performed in multiple batches,
In-Reply-To: <1238692283.5444.123.camel@ebony.2ndQuadrant>
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