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Enable parallelism for prepared statements and extended query protocol.

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Parallel query can't handle running a query only partially rather than
to completion.  However, there seems to be no way to run a statement
prepared via SQL PREPARE other than to completion, so we can enable it
there without a problem.

The situation is more complicated for the extend query protocol.
libpq seems to provide no way to send an Execute message with a
non-zero rowcount, but some other client might.  If that happens, and
a parallel plan was chosen, we'll execute the parallel plan without
using any workers, which may be somewhat inefficient but should still
work.  Hopefully this won't be a problem; users can always set
max_parallel_degree=0 to avoid choosing parallel plans in the first
place.

Amit Kapila, reviewed by me.
This commit is contained in:
Robert Haas 2016-02-25 13:02:18 +05:30
parent 25924ac47a
commit 57a6a72b6b
2 changed files with 2 additions and 2 deletions
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2
src/backend/commands/prepare.c
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@ -159,7 +159,7 @@ PrepareQuery(PrepareStmt *stmt, const char *queryString)
nargs, nargs,
NULL, NULL,
NULL, NULL,
0, /* default cursor options */ CURSOR_OPT_PARALLEL_OK, /* allow parallel mode */
true); /* fixed result */ true); /* fixed result */
/* /*

2
src/backend/tcop/postgres.c
View File

@ -1381,7 +1381,7 @@ exec_parse_message(const char *query_string, /* string to execute */
numParams, numParams,
NULL, NULL,
NULL, NULL,
0, /* default cursor options */ CURSOR_OPT_PARALLEL_OK, /* allow parallel mode */
true); /* fixed result */ true); /* fixed result */
/* If we got a cancel signal during analysis, quit */ /* If we got a cancel signal during analysis, quit */