get_table_names(): Fix reflection method to respect schema query argument

It did not respect the `schema` query argument in SQLAlchemy connection
URLs.

Co-authored-by: Marios Trivyzas <[email protected]>

Author: amotl

CHANGES.md

@@ -5,6 +5,8 @@
 - Added support for CrateDB's [FLOAT_VECTOR] data type and its accompanying
   [KNN_MATCH] function, for HNSW matches. For SQLAlchemy column definitions,
   you can use it like `FloatVector(dimensions=1536)`.
+- Fixed `get_table_names()` reflection method to respect the
+  `schema` query argument in SQLAlchemy connection URLs.
 
 [FLOAT_VECTOR]: https://cratedb.com/docs/crate/reference/en/latest/general/ddl/data-types.html#float-vector
 [KNN_MATCH]: https://cratedb.com/docs/crate/reference/en/latest/general/builtins/scalar-functions.html#scalar-knn-match

src/sqlalchemy_cratedb/dialect.py

@@ -229,6 +229,15 @@ def connect(self, host=None, port=None, *args, **kwargs):
     def _get_default_schema_name(self, connection):
         return 'doc'
 
+    def _get_effective_schema_name(self, connection):
+        schema_name_raw = connection.engine.url.query.get("schema")
+        schema_name = None
+        if isinstance(schema_name_raw, str):
+            schema_name = schema_name_raw
+        elif isinstance(schema_name_raw, tuple):
+            schema_name = schema_name_raw[0]
+        return schema_name
+
     def _get_server_version_info(self, connection):
         return tuple(connection.connection.lowest_server_version.version)
 
@@ -258,6 +267,8 @@ def get_schema_names(self, connection, **kw):
 
     @reflection.cache
     def get_table_names(self, connection, schema=None, **kw):
+        if schema is None:
+            schema = self._get_effective_schema_name(connection)
         cursor = connection.exec_driver_sql(
             "SELECT table_name FROM information_schema.tables "
             "WHERE {0} = ? "