Harrison/sql alchemy (#2216)

Co-authored-by: Jason B. Hart <jasonbhart@users.noreply.github.com>

langchain/chains/sql_database/base.py

@@ -162,7 +162,7 @@ class SQLDatabaseSequentialChain(Chain, BaseModel):
             return [self.output_key, "intermediate_steps"]
 
     def _call(self, inputs: Dict[str, str]) -> Dict[str, str]:
-        _table_names = self.sql_chain.database.get_table_names()
+        _table_names = self.sql_chain.database.get_usable_table_names()
         table_names = ", ".join(_table_names)
         llm_inputs = {
             "query": inputs[self.input_key],

langchain/sql_database.py

@@ -1,6 +1,7 @@
 """SQLAlchemy wrapper around a database."""
 from __future__ import annotations
 
+import warnings
 from typing import Any, Iterable, List, Optional
 
 from sqlalchemy import MetaData, create_engine, inspect, select, text
@@ -44,6 +45,8 @@ class SQLDatabase:
                 raise ValueError(
                     f"ignore_tables {missing_tables} not found in database"
                 )
+        usable_tables = self.get_usable_table_names()
+        self._usable_tables = set(usable_tables) if usable_tables else self._all_tables
 
         if not isinstance(sample_rows_in_table_info, int):
             raise TypeError("sample_rows_in_table_info must be an integer")
@@ -66,7 +69,9 @@ class SQLDatabase:
             )
 
         self._metadata = metadata or MetaData()
-        self._metadata.reflect(bind=self._engine)
+        self._metadata.reflect(
+            bind=self._engine, only=self._usable_tables, schema=self._schema
+        )
 
     @classmethod
     def from_uri(
@@ -81,12 +86,19 @@ class SQLDatabase:
         """Return string representation of dialect to use."""
         return self._engine.dialect.name
 
-    def get_table_names(self) -> Iterable[str]:
+    def get_usable_table_names(self) -> Iterable[str]:
         """Get names of tables available."""
         if self._include_tables:
             return self._include_tables
         return self._all_tables - self._ignore_tables
 
+    def get_table_names(self) -> Iterable[str]:
+        """Get names of tables available."""
+        warnings.warn(
+            "This method is deprecated - please use `get_usable_table_names`."
+        )
+        return self.get_usable_table_names()
+
     @property
     def table_info(self) -> str:
         """Information about all tables in the database."""
@@ -102,7 +114,7 @@ class SQLDatabase:
         appended to each table description. This can increase performance as
         demonstrated in the paper.
         """
-        all_table_names = self.get_table_names()
+        all_table_names = self.get_usable_table_names()
         if table_names is not None:
             missing_tables = set(table_names).difference(all_table_names)
             if missing_tables:

langchain/tools/sql_database/tool.py

@@ -69,7 +69,7 @@ class ListSQLDatabaseTool(BaseSQLDatabaseTool, BaseTool):
 
     def _run(self, tool_input: str = "") -> str:
         """Get the schema for a specific table."""
-        return ", ".join(self.db.get_table_names())
+        return ", ".join(self.db.get_usable_table_names())
 
     async def _arun(self, tool_input: str = "") -> str:
         raise NotImplementedError("ListTablesSqlDbTool does not support async")