pgsql: Dept of second thoughts: don't try to push LIMIT below a SRF.

Dept of second thoughts: don't try to push LIMIT below a SRF.

If we have Limit->Result->Sort, the Result might be projecting a tlist
that contains a set-returning function.  If so, it's possible for the
SRF to sometimes return zero rows, which means we could need to fetch
more than N rows from the Sort in order to satisfy LIMIT N.
So top-N sorting cannot be used in this scenario.

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=48c348f86ce09c668af7cf271757c3f156f28344

Modified Files
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src/backend/executor/nodeLimit.c |   15 ++++++++++++++-
1 files changed, 14 insertions(+), 1 deletions(-)