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+++ b/examples/trac/trac/db/postgres_backend.py
@@ -0,0 +1,148 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2005 Edgewall Software
+# Copyright (C) 2005 Christopher Lenz <cmlenz@gmx.de>
+# All rights reserved.
+#
+# This software is licensed as described in the file COPYING, which
+# you should have received as part of this distribution. The terms
+# are also available at http://trac.edgewall.com/license.html.
+#
+# This software consists of voluntary contributions made by many
+# individuals. For the exact contribution history, see the revision
+# history and logs, available at http://projects.edgewall.com/trac/.
+#
+# Author: Christopher Lenz <cmlenz@gmx.de>
+
+import re
+
+from trac.core import *
+from trac.db.api import IDatabaseConnector
+from trac.db.util import ConnectionWrapper
+
+psycopg = None
+PgSQL = None
+PGSchemaError = None
+
+_like_escape_re = re.compile(r'([/_%])')
+
+
+class PostgreSQLConnector(Component):
+    """PostgreSQL database support."""
+
+    implements(IDatabaseConnector)
+
+    def get_supported_schemes(self):
+        return [('postgres', 1)]
+
+    def get_connection(self, path, user=None, password=None, host=None,
+                       port=None, params={}):
+        return PostgreSQLConnection(path, user, password, host, port, params)
+
+    def init_db(self, path, user=None, password=None, host=None, port=None,
+                params={}):
+        cnx = self.get_connection(path, user, password, host, port, params)
+        cursor = cnx.cursor()
+        if cnx.schema:
+            cursor.execute('CREATE SCHEMA %s' % cnx.schema)
+            cursor.execute('SET search_path TO %s, public', (cnx.schema,))
+        from trac.db_default import schema
+        for table in schema:
+            for stmt in self.to_sql(table):
+                cursor.execute(stmt)
+        cnx.commit()
+
+    def to_sql(self, table):
+        sql = ["CREATE TABLE %s (" % table.name]
+        coldefs = []
+        for column in table.columns:
+            ctype = column.type
+            if column.auto_increment:
+                ctype = "SERIAL"
+            if len(table.key) == 1 and column.name in table.key:
+                ctype += " PRIMARY KEY"
+            coldefs.append("    %s %s" % (column.name, ctype))
+        if len(table.key) > 1:
+            coldefs.append("    CONSTRAINT %s_pk PRIMARY KEY (%s)"
+                           % (table.name, ','.join(table.key)))
+        sql.append(',\n'.join(coldefs) + '\n)')
+        yield '\n'.join(sql)
+        for index in table.indices:
+            yield "CREATE INDEX %s_%s_idx ON %s (%s)" % (table.name, 
+                   '_'.join(index.columns), table.name, ','.join(index.columns))
+
+
+class PostgreSQLConnection(ConnectionWrapper):
+    """Connection wrapper for PostgreSQL."""
+
+    poolable = True
+
+    def __init__(self, path, user=None, password=None, host=None, port=None,
+                 params={}):
+        if path.startswith('/'):
+            path = path[1:]
+        # We support both psycopg and PgSQL but prefer psycopg
+        global psycopg
+        global PgSQL
+        global PGSchemaError
+        
+        if not psycopg and not PgSQL:
+            try:
+                import psycopg2 as psycopg
+                import psycopg2.extensions
+                from psycopg2 import ProgrammingError as PGSchemaError
+                psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
+            except ImportError:
+                from pyPgSQL import PgSQL
+                from pyPgSQL.libpq import OperationalError as PGSchemaError
+        if psycopg:
+            dsn = []
+            if path:
+                dsn.append('dbname=' + path)
+            if user:
+                dsn.append('user=' + user)
+            if password:
+                dsn.append('password=' + password)
+            if host:
+                dsn.append('host=' + host)
+            if port:
+                dsn.append('port=' + str(port))
+            cnx = psycopg.connect(' '.join(dsn))
+            cnx.set_client_encoding('UNICODE')
+        else:
+            cnx = PgSQL.connect('', user, password, host, path, port, 
+                                client_encoding='utf-8', unicode_results=True)
+        try:
+            self.schema = None
+            if 'schema' in params:
+                self.schema = params['schema']
+            cnx.cursor().execute('SET search_path TO %s, public', 
+                                (self.schema,))
+        except PGSchemaError:
+            cnx.rollback()
+        ConnectionWrapper.__init__(self, cnx)
+
+    def cast(self, column, type):
+        # Temporary hack needed for the union of selects in the search module
+        return 'CAST(%s AS %s)' % (column, type)
+
+    def like(self):
+        # Temporary hack needed for the case-insensitive string matching in the
+        # search module
+        return "ILIKE %s ESCAPE '/'"
+
+    def like_escape(self, text):
+        return _like_escape_re.sub(r'/\1', text)
+
+    def get_last_id(self, cursor, table, column='id'):
+        cursor.execute("SELECT CURRVAL('%s_%s_seq')" % (table, column))
+        return cursor.fetchone()[0]
+
+    def rollback(self):
+        self.cnx.rollback()
+        if self.schema:
+            try:
+                self.cnx.cursor().execute("SET search_path TO %s, public", 
+                                         (self.schema,))
+            except PGSchemaError:
+                self.cnx.rollback()