X-Git-Url: https://git.openstreetmap.org./nominatim.git/blobdiff_plain/d78f0ba80470a33a7a76edfe3ace5108684873cd..f08078ccca8077b09f4b1cbb8991a4ecf7257cc4:/nominatim/db/connection.py

diff --git a/nominatim/db/connection.py b/nominatim/db/connection.py
index 8e75d7a2..b941f46f 100644
--- a/nominatim/db/connection.py
+++ b/nominatim/db/connection.py
@@ -7,6 +7,8 @@ import psycopg2
 import psycopg2.extensions
 import psycopg2.extras
 
+from ..errors import UsageError
+
 class _Cursor(psycopg2.extras.DictCursor):
     """ A cursor returning dict-like objects and providing specialised
         execution functions.
@@ -27,7 +29,7 @@ class _Cursor(psycopg2.extras.DictCursor):
         self.execute(sql, args)
 
         if self.rowcount != 1:
-            raise ValueError("Query did not return a single row.")
+            raise RuntimeError("Query did not return a single row.")
 
         return self.fetchone()[0]
 
@@ -42,17 +44,49 @@ class _Connection(psycopg2.extensions.connection):
         """
         return super().cursor(cursor_factory=cursor_factory, **kwargs)
 
+
     def table_exists(self, table):
         """ Check that a table with the given name exists in the database.
         """
         with self.cursor() as cur:
             num = cur.scalar("""SELECT count(*) FROM pg_tables
-                                WHERE tablename = %s""", (table, ))
+                                WHERE tablename = %s and schemaname = 'public'""", (table, ))
             return num == 1
 
 
+    def index_exists(self, index, table=None):
+        """ Check that an index with the given name exists in the database.
+            If table is not None then the index must relate to the given
+            table.
+        """
+        with self.cursor() as cur:
+            cur.execute("""SELECT tablename FROM pg_indexes
+                           WHERE indexname = %s and schemaname = 'public'""", (index, ))
+            if cur.rowcount == 0:
+                return False
+
+            if table is not None:
+                row = cur.fetchone()
+                return row[0] == table
+
+        return True
+
+
+    def server_version_tuple(self):
+        """ Return the server version as a tuple of (major, minor).
+            Converts correctly for pre-10 and post-10 PostgreSQL versions.
+        """
+        version = self.server_version
+        if version < 100000:
+            return (version / 10000, (version % 10000) / 100)
+
+        return (version / 10000, version % 10000)
+
 def connect(dsn):
     """ Open a connection to the database using the specialised connection
         factory.
     """
-    return psycopg2.connect(dsn, connection_factory=_Connection)
+    try:
+        return psycopg2.connect(dsn, connection_factory=_Connection)
+    except psycopg2.OperationalError as err:
+        raise UsageError("Cannot connect to database: {}".format(err)) from err