--- a/roundup/backends/back_postgresql.py	Sat Dec 23 21:59:08 2023 -0500
+++ b/roundup/backends/back_postgresql.py	Wed Dec 27 22:52:14 2023 -0500
@@ -9,6 +9,7 @@
 
 import logging
 import os
+import re
 import shutil
 import time
 
@@ -47,28 +48,40 @@
         del d['read_default_file']
     return d
 
+def db_schema_split(database_name):
+    ''' Split database_name into database and schema parts'''
+    if '.' in database_name:
+        return database_name.split ('.')
+    return [database_name, '']
 
 def db_create(config):
     """Clear all database contents and drop database itself"""
-    command = ("CREATE DATABASE \"%s\" WITH ENCODING='UNICODE'" % 
-               get_database_name(config))
-    if config.RDBMS_TEMPLATE:
-        command = command + " TEMPLATE=%s" % config.RDBMS_TEMPLATE
-    logging.getLogger('roundup.hyperdb').info(command)
-    db_command(config, command)
-
+    db_name, schema_name = db_schema_split(config.RDBMS_NAME)
+    if not schema_name:
+        command = "CREATE DATABASE \"%s\" WITH ENCODING='UNICODE'" % db_name
+        if config.RDBMS_TEMPLATE:
+            command = command + " TEMPLATE=%s" % config.RDBMS_TEMPLATE
+        logging.getLogger('roundup.hyperdb').info(command)
+        db_command(config, command)
+    else:
+        command = "CREATE SCHEMA \"%s\" AUTHORIZATION \"%s\"" % (schema_name, config.RDBMS_USER)
+        logging.getLogger('roundup.hyperdb').info(command)
+        db_command(config, command, db_name)
 
 def db_nuke(config):
-    """Clear all database contents and drop database itself"""
-    command = 'DROP DATABASE "%s"' % get_database_name(config)
-
-    logging.getLogger('roundup.hyperdb').info(command)
-    db_command(config, command)
-
+    """Drop the database (and all its contents) or the schema."""
+    db_name, schema_name = db_schema_split(config.RDBMS_NAME)
+    if not schema_name:
+        command = 'DROP DATABASE "%s"'% db_name
+        logging.getLogger('roundup.hyperdb').info(command)
+        db_command(config, command)
+    else:
+        command = 'DROP SCHEMA "%s" CASCADE' % schema_name
+        logging.getLogger('roundup.hyperdb').info(command)
+        db_command(config, command, db_name)
     if os.path.exists(config.DATABASE):
         shutil.rmtree(config.DATABASE)
 
-
 def get_database_name(config):
     '''Get database name using config.RDBMS_NAME or config.RDBMS_SERVICE.
 
@@ -124,14 +137,16 @@
     before "template1" seems to have been used, so we fall back to it.
     Compare to issue2550543.
     '''
-    template1 = connection_dict(config)
+    template1 = connection_dict(config, 'database')
+    db_name, schema_name = db_schema_split(template1['database'])
     template1['database'] = database
 
     try:
         conn = psycopg2.connect(**template1)
     except psycopg2.OperationalError as message:
-        if str(message).find('database "postgres" does not exist') >= 0:
-            return db_command(config, command, database='template1')
+        if not schema_name:
+            if re.search(r'database ".+" does not exist', str(message)):
+                return db_command(config, command, database='template1')
         raise hyperdb.DatabaseError(message)
 
     conn.set_isolation_level(0)
@@ -142,17 +157,17 @@
                 return
     finally:
         conn.close()
-    raise RuntimeError('10 attempts to create database failed when running: %s' % command)
+    raise RuntimeError('10 attempts to create database or schema failed when running: %s' % command)
 
 
-def pg_command(cursor, command):
+def pg_command(cursor, command, args=()):
     '''Execute the postgresql command, which may be blocked by some other
     user connecting to the database, and return a true value if it succeeds.
 
     If there is a concurrent update, retry the command.
     '''
     try:
-        cursor.execute(command)
+        cursor.execute(command, args)
     except psycopg2.DatabaseError as err:
         response = str(err).split('\n')[0]
         if "FATAL" not in response:
@@ -164,19 +179,32 @@
                 if msg in response:
                     time.sleep(0.1)
                     return 0
-        raise RuntimeError(response)
+        raise RuntimeError(response, command, args)
     return 1
 
 
 def db_exists(config):
-    """Check if database already exists"""
+    """Check if database or schema already exists"""
     db = connection_dict(config, 'database')
+    db_name, schema_name = db_schema_split(db['database'])
+    if schema_name:
+        db['database'] = db_name
     try:
         conn = psycopg2.connect(**db)
-        conn.close()
-        return 1
+        if not schema_name:
+            conn.close()
+            return 1
     except Exception:
         return 0
+    # <schema_name> will have a non-false value here; otherwise one
+    #  of the above returns would have returned.
+    # Get a count of the number of schemas named <schema_name> (either 0 or 1).
+    command = "SELECT COUNT(*) FROM information_schema.schemata WHERE schema_name = %s"
+    cursor = conn.cursor()
+    pg_command(cursor, command, (schema_name,))
+    count = cursor.fetchall()[0][0]
+    conn.close()
+    return count    # 'count' will be 0 or 1.
 
 
 class Sessions(sessions_rdbms.Sessions):
@@ -225,6 +253,10 @@
 
     def sql_open_connection(self):
         db = connection_dict(self.config, 'database')
+        db_name, schema_name = db_schema_split (db['database'])
+        if schema_name:
+            db['database'] = db_name
+
         # database option always present: log it if not null
         if db['database']:
             logging.getLogger('roundup.hyperdb').info(
@@ -242,6 +274,11 @@
             lvl = isolation_levels[self.config.RDBMS_ISOLATION_LEVEL]
             conn.set_isolation_level(lvl)
 
+        if schema_name:
+            self.sql ('SET search_path TO %s' % schema_name, cursor=cursor)
+            # Commit is required so that a subsequent rollback
+            #  will not also rollback the search_path change.
+            self.sql ('COMMIT', cursor=cursor)
         return (conn, cursor)
 
     def sql_new_cursor(self, name='default', conn=None, *args, **kw):