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| author | Robert Haas <rhaas@postgresql.org> | 2011-12-21 09:16:55 -0500 |
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| committer | Robert Haas <rhaas@postgresql.org> | 2011-12-21 09:16:55 -0500 |
| commit | d573e239f03506920938bf0be56c868d9c3416da (patch) | |
| tree | 204b429f7ae848e4413f7df75fc7f98dca0e084e /src/backend/commands/cluster.c | |
| parent | e1042a348421bc16f4d4307228a9951e38a984f1 (diff) | |
| download | postgresql-d573e239f03506920938bf0be56c868d9c3416da.tar.gz postgresql-d573e239f03506920938bf0be56c868d9c3416da.zip | |
Take fewer snapshots.
When a PORTAL_ONE_SELECT query is executed, we can opportunistically
reuse the parse/plan shot for the execution phase. This cuts down the
number of snapshots per simple query from 2 to 1 for the simple
protocol, and 3 to 2 for the extended protocol. Since we are only
reusing a snapshot taken early in the processing of the same protocol
message, the change shouldn't be user-visible, except that the remote
possibility of the planning and execution snapshots being different is
eliminated.
Note that this change does not make it safe to assume that the parse/plan
snapshot will certainly be reused; that will currently only happen if
PortalStart() decides to use the PORTAL_ONE_SELECT strategy. It might
be worth trying to provide some stronger guarantees here in the future,
but for now we don't.
Patch by me; review by Dimitri Fontaine.
Diffstat (limited to 'src/backend/commands/cluster.c')
0 files changed, 0 insertions, 0 deletions