Skip site navigation (1) Skip section navigation (2)

pgsql: Fix mark_placeholder_maybe_needed to handle LATERAL references.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Fix mark_placeholder_maybe_needed to handle LATERAL references.
Date: 2012-09-01 17:57:02
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-committers
Fix mark_placeholder_maybe_needed to handle LATERAL references.

If a PlaceHolderVar contains a pulled-up LATERAL reference, its minimum
possible evaluation level might be higher in the join tree than its
original syntactic location.  That in turn affects the ph_needed level for
any contained PlaceHolderVars (that is, those PHVs had better propagate up
the join tree at least to the evaluation level of the outer PHV).  We got
this mostly right, but mark_placeholder_maybe_needed() failed to account
for the effect, and in consequence could leave the inner PHVs with
ph_may_need less than what their ultimate ph_needed value will be.  That's
bad because it could lead to failure to select a join order that will allow
evaluation of the inner PHV at a valid location.  Fix that, and add an
Assert that checks that we don't ever set ph_needed to more than



Modified Files
src/backend/optimizer/plan/initsplan.c   |    5 +++-
src/backend/optimizer/util/placeholder.c |   15 +++++++++--
src/test/regress/expected/join.out       |   40 ++++++++++++++++++++++++++++++
src/test/regress/sql/join.sql            |   11 ++++++++
4 files changed, 67 insertions(+), 4 deletions(-)

pgsql-committers by date

Next:From: Tom LaneDate: 2012-09-01 22:16:38
Subject: pgsql: Drop cheap-startup-cost paths during add_path() if we don'tneed
Previous:From: Bruce MomjianDate: 2012-09-01 16:05:05
Subject: pgsql: Revert doc patch 305557984dd964ac397c6752e9d0f14646b60f15 asthe

Privacy Policy | About PostgreSQL
Copyright © 1996-2018 The PostgreSQL Global Development Group