From 6bebb23318c5a2195a89a7154118cfc5ea19bba7 Mon Sep 17 00:00:00 2001
From: Malcolm Tredinnick <malcolm.tredinnick@gmail.com>
Date: Tue, 12 Aug 2008 06:31:29 +0000
Subject: [PATCH] Do not use savepoints with PostgreSQL prior to 8.0.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8317 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/db/backends/postgresql/base.py          |  7 +++++++
 django/db/backends/postgresql/version.py       | 18 ++++++++++++++++++
 django/db/backends/postgresql_psycopg2/base.py |  7 +++++++
 3 files changed, 32 insertions(+)
 create mode 100644 django/db/backends/postgresql/version.py

diff --git a/django/db/backends/postgresql/base.py b/django/db/backends/postgresql/base.py
index 792026530f..7bcda5b6f6 100644
--- a/django/db/backends/postgresql/base.py
+++ b/django/db/backends/postgresql/base.py
@@ -9,6 +9,7 @@ from django.db.backends.postgresql.client import DatabaseClient
 from django.db.backends.postgresql.creation import DatabaseCreation
 from django.db.backends.postgresql.introspection import DatabaseIntrospection
 from django.db.backends.postgresql.operations import DatabaseOperations
+from django.db.backends.postgresql.version import get_version
 from django.utils.encoding import smart_str, smart_unicode
 
 try:
@@ -115,6 +116,12 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         cursor = self.connection.cursor()
         if set_tz:
             cursor.execute("SET TIME ZONE %s", [settings.TIME_ZONE])
+            if not hasattr(self, '_version'):
+                version = get_version(cursor)
+                self.__class__._version = version
+                if version < (8, 0):
+                    # No savepoint support for earlier version of PostgreSQL.
+                    self.features.uses_savepoints = False
         cursor.execute("SET client_encoding to 'UNICODE'")
         cursor = UnicodeCursorWrapper(cursor, 'utf-8')
         return cursor
diff --git a/django/db/backends/postgresql/version.py b/django/db/backends/postgresql/version.py
new file mode 100644
index 0000000000..e14d791b07
--- /dev/null
+++ b/django/db/backends/postgresql/version.py
@@ -0,0 +1,18 @@
+"""
+Extracts the version of the PostgreSQL server.
+"""
+
+import re
+
+VERSION_RE = re.compile(r'PostgreSQL (\d+)\.(\d+)\.')
+
+def get_version(cursor):
+    """
+    Returns a tuple representing the major and minor version number of the
+    server. For example, (7, 4) or (8, 3).
+    """
+    cursor.execute("SELECT version()")
+    version = cursor.fetchone()[0]
+    major, minor = VERSION_RE.search(version).groups()
+    return int(major), int(minor)
+
diff --git a/django/db/backends/postgresql_psycopg2/base.py b/django/db/backends/postgresql_psycopg2/base.py
index 08014bd993..b50cb1d1c9 100644
--- a/django/db/backends/postgresql_psycopg2/base.py
+++ b/django/db/backends/postgresql_psycopg2/base.py
@@ -8,6 +8,7 @@ from django.db.backends import *
 from django.db.backends.postgresql.operations import DatabaseOperations as PostgresqlDatabaseOperations
 from django.db.backends.postgresql.client import DatabaseClient
 from django.db.backends.postgresql.creation import DatabaseCreation
+from django.db.backends.postgresql.version import get_version
 from django.db.backends.postgresql_psycopg2.introspection import DatabaseIntrospection
 
 from django.utils.safestring import SafeUnicode
@@ -86,4 +87,10 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         cursor.tzinfo_factory = None
         if set_tz:
             cursor.execute("SET TIME ZONE %s", [settings.TIME_ZONE])
+            if not hasattr(self, '_version'):
+                version = get_version(cursor)
+                self.__class__._version = version
+                if version < (8, 0):
+                    # No savepoint support for earlier version of PostgreSQL.
+                    self.features.uses_savepoints = False
         return cursor