Implementation of CITEXT , unittest and documentation

Added new PostgreSQL type :class:`_postgresql.CITEXT`. Pull request
courtesy Julian David Rath.

Fixes: #9416
Closes: #9417
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/9417
Pull-request-sha: 23a83a342ad6d820ee5749ebccda04e54c373f7d

Change-Id: I54699b9457426c20afbdc0acaa41dc57644b0536

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/provision.py b/lib/sqlalchemy/dialects/postgresql/provision.py
index 4609701a2..5c6b9fcea 100644
--- a/lib/sqlalchemy/dialects/postgresql/provision.py
+++ b/lib/sqlalchemy/dialects/postgresql/provision.py
@@ -11,6 +11,7 @@ from ...testing.provision import drop_all_schema_objects_post_tables
 from ...testing.provision import drop_all_schema_objects_pre_tables
 from ...testing.provision import drop_db
 from ...testing.provision import log
+from ...testing.provision import post_configure_engine
 from ...testing.provision import prepare_for_drop_tables
 from ...testing.provision import set_default_schema_on_connection
 from ...testing.provision import temp_table_keyword_args
@@ -145,3 +146,11 @@ def _upsert(cfg, table, returning, set_lambda=None):
 
     stmt = stmt.returning(*returning)
     return stmt
+
+
+@post_configure_engine.for_db("postgresql")
+def _create_citext_extension(url, engine, follower_ident):
+    with engine.connect() as conn:
+        if conn.dialect.server_version_info >= (13,):
+            conn.execute(text("CREATE EXTENSION IF NOT EXISTS citext"))
+            conn.commit()