Re: [COMMITTERS] pgsql: Fix parameter recalculation for Limit nodes: during a ReScan call

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)postgresql(dot)org>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [COMMITTERS] pgsql: Fix parameter recalculation for Limit nodes: during a ReScan call
Date: 2007-05-17 21:33:44
Message-ID: 200705172133.l4HLXiB11279@momjian.us
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Is there still a TODO here?

---------------------------------------------------------------------------

Tom Lane wrote:
> Log Message:
> -----------
> Fix parameter recalculation for Limit nodes: during a ReScan call we must
> recompute the limit/offset immediately, so that the updated values are
> available when the child's ReScan function is invoked. Add a regression
> test for this, too. Bug is new in HEAD (due to the bounded-sorting patch)
> so no need for back-patch.
>
> I did not do anything about merging this signaling with chgParam processing,
> but if we were to do that we'd still need to compute the updated values
> at this point rather than during the first ProcNode call.
>
> Per observation and test case from Greg Stark, though I didn't use his patch.
>
> Modified Files:
> --------------
> pgsql/src/backend/executor:
> nodeLimit.c (r1.30 -> r1.31)
> (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeLimit.c.diff?r1=1.30&r2=1.31)
> nodeSubplan.c (r1.88 -> r1.89)
> (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeSubplan.c.diff?r1=1.88&r2=1.89)
> pgsql/src/include/nodes:
> execnodes.h (r1.173 -> r1.174)
> (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/execnodes.h.diff?r1=1.173&r2=1.174)
> pgsql/src/test/regress/expected:
> limit.out (r1.4 -> r1.5)
> (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/limit.out.diff?r1=1.4&r2=1.5)
> pgsql/src/test/regress/sql:
> limit.sql (r1.4 -> r1.5)
> (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/limit.sql.diff?r1=1.4&r2=1.5)
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: don't forget to increase your free space map settings

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Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
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