Add indexing support for postgresql (#9933)

Add support to postgresql for the SQL Manager Record

This code was tested locally. I'm looking at how to add testing with
postgres in a separate PR.

libs/langchain/langchain/indexes/_api.py

@@ -332,9 +332,9 @@ def index(
         uids_to_delete = record_manager.list_keys(before=index_start_dt)
 
         if uids_to_delete:
-            # Then delete from vector store.
-            vector_store.delete(uids_to_delete)
             # First delete from record store.
+            vector_store.delete(uids_to_delete)
+            # Then delete from record manager.
             record_manager.delete_keys(uids_to_delete)
             num_deleted = len(uids_to_delete)
 

libs/langchain/langchain/indexes/_sql_record_manager.py

@@ -14,10 +14,12 @@ allow it to work with a variety of SQL as a backend.
 * Keys can be deleted.
 """
 import contextlib
+import decimal
 import uuid
-from typing import Any, Dict, Generator, List, Optional, Sequence
+from typing import Any, Dict, Generator, List, Optional, Sequence, Union
 
 from sqlalchemy import (
+    URL,
     Column,
     Engine,
     Float,
@@ -28,7 +30,6 @@ from sqlalchemy import (
     create_engine,
     text,
 )
-from sqlalchemy.dialects.sqlite import insert
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import Session, sessionmaker
 
@@ -77,7 +78,7 @@ class SQLRecordManager(RecordManager):
         namespace: str,
         *,
         engine: Optional[Engine] = None,
-        db_url: Optional[str] = None,
+        db_url: Union[None, str, URL] = None,
         engine_kwargs: Optional[Dict[str, Any]] = None,
     ) -> None:
         """Initialize the SQLRecordManager.
@@ -114,6 +115,7 @@ class SQLRecordManager(RecordManager):
             raise AssertionError("Something went wrong with configuration of engine.")
 
         self.engine = _engine
+        self.dialect = _engine.dialect.name
         self.session_factory = sessionmaker(bind=self.engine)
 
     def create_schema(self) -> None:
@@ -145,8 +147,16 @@ class SQLRecordManager(RecordManager):
             # 2440587.5 - constant represents the Julian day number for January 1, 1970
             # 86400.0 - constant represents the number of seconds
             # in a day (24 hours * 60 minutes * 60 seconds)
+            if self.dialect == "sqlite":
                 query = text("SELECT (julianday('now') - 2440587.5) * 86400.0;")
+            elif self.dialect == "postgresql":
+                query = text("SELECT EXTRACT (EPOCH FROM CURRENT_TIMESTAMP);")
+            else:
+                raise NotImplementedError(f"Not implemented for dialect {self.dialect}")
+
             dt = session.execute(query).scalar()
+            if isinstance(dt, decimal.Decimal):
+                dt = float(dt)
             if not isinstance(dt, float):
                 raise AssertionError(f"Unexpected type for datetime: {type(dt)}")
             return dt
@@ -192,9 +202,12 @@ class SQLRecordManager(RecordManager):
         ]
 
         with self._make_session() as session:
+            if self.dialect == "sqlite":
+                from sqlalchemy.dialects.sqlite import insert as sqlite_insert
+
                 # Note: uses SQLite insert to make on_conflict_do_update work.
                 # This code needs to be generalized a bit to work with more dialects.
-            insert_stmt = insert(UpsertionRecord).values(records_to_upsert)
+                insert_stmt = sqlite_insert(UpsertionRecord).values(records_to_upsert)
                 stmt = insert_stmt.on_conflict_do_update(  # type: ignore[attr-defined]
                     [UpsertionRecord.key, UpsertionRecord.namespace],
                     set_=dict(
@@ -203,6 +216,23 @@ class SQLRecordManager(RecordManager):
                         group_id=insert_stmt.excluded.group_id,  # type: ignore
                     ),
                 )
+            elif self.dialect == "postgresql":
+                from sqlalchemy.dialects.postgresql import insert as pg_insert
+
+                # Note: uses SQLite insert to make on_conflict_do_update work.
+                # This code needs to be generalized a bit to work with more dialects.
+                insert_stmt = pg_insert(UpsertionRecord).values(records_to_upsert)
+                stmt = insert_stmt.on_conflict_do_update(  # type: ignore[attr-defined]
+                    "uix_key_namespace",  # Name of constraint
+                    set_=dict(
+                        # attr-defined type ignore
+                        updated_at=insert_stmt.excluded.updated_at,  # type: ignore
+                        group_id=insert_stmt.excluded.group_id,  # type: ignore
+                    ),
+                )
+            else:
+                raise NotImplementedError(f"Unsupported dialect {self.dialect}")
+
             session.execute(stmt)
             session.commit()