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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2010-09-28 12:08:56 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2010-09-28 14:19:00 -0400 |
| commit | eb229505103eb5494c33832d422584bfdee03fc6 (patch) | |
| tree | ca7c12732d170cb5abef8f108b2d95f508444b7c /doc/src | |
| parent | 9c5f4f6cb50dd22028acc0b6f20291a5edcac62b (diff) | |
| download | postgresql-eb229505103eb5494c33832d422584bfdee03fc6.tar.gz postgresql-eb229505103eb5494c33832d422584bfdee03fc6.zip | |
Fix PlaceHolderVar mechanism's interaction with outer joins.
The point of a PlaceHolderVar is to allow a non-strict expression to be
evaluated below an outer join, after which its value bubbles up like a Var
and can be forced to NULL when the outer join's semantics require that.
However, there was a serious design oversight in that, namely that we
didn't ensure that there was actually a correct place in the plan tree
to evaluate the placeholder :-(. It may be necessary to delay evaluation
of an outer join to ensure that a placeholder that should be evaluated
below the join can be evaluated there. Per recent bug report from Kirill
Simonov.
Back-patch to 8.4 where the PlaceHolderVar mechanism was introduced.
Diffstat (limited to 'doc/src')
0 files changed, 0 insertions, 0 deletions