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| author | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2008-05-12 20:02:02 +0000 |
|---|---|---|
| committer | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2008-05-12 20:02:02 +0000 |
| commit | 5da9da71c44f27ba48fdad08ef263bf70e43e689 (patch) | |
| tree | d8afb52acd9386a59c1862a265d4f8e6d2fdbaba /src/backend/commands/trigger.c | |
| parent | aa82790fcab98b8d3d4eca2e2f6f7bfce57870bc (diff) | |
| download | postgresql-5da9da71c44f27ba48fdad08ef263bf70e43e689.tar.gz postgresql-5da9da71c44f27ba48fdad08ef263bf70e43e689.zip | |
Improve snapshot manager by keeping explicit track of snapshots.
There are two ways to track a snapshot: there's the "registered" list, which
is used for arbitrary long-lived snapshots; and there's the "active stack",
which is used for the snapshot that is considered "active" at any time.
This also allows users of snapshots to stop worrying about snapshot memory
allocation and freeing, and about using PG_TRY blocks around ActiveSnapshot
assignment. This is all done automatically now.
As a consequence, this allows us to reset MyProc->xmin when there are no
more snapshots registered in the current backend, reducing the impact that
long-running transactions have on VACUUM.
Diffstat (limited to 'src/backend/commands/trigger.c')
| -rw-r--r-- | src/backend/commands/trigger.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c index 1ec24812d71..7685906aeb0 100644 --- a/src/backend/commands/trigger.c +++ b/src/backend/commands/trigger.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.232 2008/05/12 00:00:48 alvherre Exp $ + * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.233 2008/05/12 20:01:59 alvherre Exp $ * *------------------------------------------------------------------------- */ @@ -2976,6 +2976,7 @@ void AfterTriggerFireDeferred(void) { AfterTriggerEventList *events; + bool snap_pushed = false; /* Must be inside a transaction */ Assert(afterTriggers != NULL); @@ -2990,7 +2991,10 @@ AfterTriggerFireDeferred(void) */ events = &afterTriggers->events; if (events->head != NULL) - ActiveSnapshot = CopySnapshot(GetTransactionSnapshot()); + { + PushActiveSnapshot(GetTransactionSnapshot()); + snap_pushed = true; + } /* * Run all the remaining triggers. Loop until they are all gone, in case @@ -3003,6 +3007,9 @@ AfterTriggerFireDeferred(void) afterTriggerInvokeEvents(events, firing_id, NULL, true); } + if (snap_pushed) + PopActiveSnapshot(); + Assert(events->head == NULL); } |