From 5da9da71c44f27ba48fdad08ef263bf70e43e689 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Mon, 12 May 2008 20:02:02 +0000 Subject: 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. --- src/backend/tcop/fastpath.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'src/backend/tcop/fastpath.c') diff --git a/src/backend/tcop/fastpath.c b/src/backend/tcop/fastpath.c index 80cf04680a9..90848112580 100644 --- a/src/backend/tcop/fastpath.c +++ b/src/backend/tcop/fastpath.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/tcop/fastpath.c,v 1.99 2008/03/26 18:48:59 alvherre Exp $ + * $PostgreSQL: pgsql/src/backend/tcop/fastpath.c,v 1.100 2008/05/12 20:02:01 alvherre Exp $ * * NOTES * This cruft is the server side of PQfn. @@ -309,7 +309,7 @@ HandleFunctionRequest(StringInfo msgBuf) * Now that we know we are in a valid transaction, set snapshot in case * needed by function itself or one of the datatype I/O routines. */ - ActiveSnapshot = CopySnapshot(GetTransactionSnapshot()); + PushActiveSnapshot(GetTransactionSnapshot()); /* * Begin parsing the buffer contents. @@ -396,6 +396,9 @@ HandleFunctionRequest(StringInfo msgBuf) SendFunctionResult(retval, fcinfo.isnull, fip->rettype, rformat); + /* We no longer need the snapshot */ + PopActiveSnapshot(); + /* * Emit duration logging if appropriate. */ -- cgit v1.2.3