From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | pgsql-committers(at)postgresql(dot)org |
Subject: | pgsql: Fix up parallel-safety marking for appendrels. |
Date: | 2016-07-03 21:57:34 |
Message-ID: | E1bJpOQ-00077w-Ge@gemulon.postgresql.org |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-committers |
Fix up parallel-safety marking for appendrels.
The previous coding assumed that the value derived by
set_rel_consider_parallel() for an appendrel parent would be accurate for
all the appendrel's children; but this is not so, for example because one
child might scan a temp table. Instead, apply set_rel_consider_parallel()
to each child rel as well as the parent, and then take the AND of the
results as controlling parallel safety for the appendrel as a whole.
(We might someday be able to deal more intelligently than this with cases
in which some of the childrels are parallel-safe and others not, but that's
for later.)
Robert Haas and Tom Lane
Branch
------
master
Details
-------
http://git.postgresql.org/pg/commitdiff/4ea9948e58a57316330acb1701f979bc1e872f50
Modified Files
--------------
src/backend/optimizer/path/allpaths.c | 73 ++++++++++++++++++++++++++++-------
1 file changed, 58 insertions(+), 15 deletions(-)
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2016-07-03 22:24:55 | pgsql: Allow RTE_SUBQUERY rels to be considered parallel-safe. |
Previous Message | Tom Lane | 2016-07-03 20:55:33 | pgsql: Allow treating TABLESAMPLE scans as parallel-safe. |