I opened ticket 2497 to remove redundant BEGIN sql calls for postgis
layers which use pooled connections. A proposed patch is submitted in trac.
Thanks,
Dave Fuhry
-------- Original Message --------
Subject: [MapServer] #2497: mappostgis.c: BEGIN transaction once in
msPOSTGISLayerOpen rather than repeatedly in prepare_database
Date: Fri, 08 Feb 2008 00:54:57 -0000
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#2497: mappostgis.c: BEGIN transaction once in msPOSTGISLayerOpen rather
than repeatedly in prepare_database
---------------------------------+------------------------------------------
Reporter: dfuhry | Owner: sdlime
Type: defect | Status: new
Priority: normal | Milestone: 5.2 release
Component: MapServer C Library | Version: svn-trunk (development)
Severity: normal | Keywords: postgis transaction begin
---------------------------------+------------------------------------------
Currently, mappostgis.c in prepare_database() issues a
PQexec(layerinfo->conn, "BEGIN") every time a postgis layer is rendered,
even if CLOSE_CONNECTION=DEFER is set for the layer.
Since the db connection is recycled, this makes unnecessary calls to
the database and results in a:
WARNING: there is already a transaction in progress
message in the postgresql log file each time a postgis layer is
rendered. The per-layer call gives no extra safety since a redundant
BEGIN will not start a new transaction, nor will one "fix" a transaction
in which an error has occurred.
All postgis queries are "DECLARE CURSOR ..." so a transaction is
necessary, but the transaction can be started when the layer is opened.
The proposed patch moves the PQexec(layerinfo->conn, "BEGIN") call to
msPOSTGISLayerOpen(), so that it will be issued only once when the
connection is opened.
Tested on Linux with CLOSE_CONNECTION=DEFER layers and FastCGI.
--
Ticket URL: <
http://trac.osgeo.org/mapserver/ticket/2497>
MapServer <
http://mapserver.gis.umn.edu>
MapServer
