init
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332
vw-agentic-rag/service/memory/postgresql_memory.py
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332
vw-agentic-rag/service/memory/postgresql_memory.py
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"""
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PostgreSQL-based memory implementation using LangGraph built-in components.
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Provides session-level chat history with 7-day TTL.
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Uses psycopg3 for better compatibility without requiring libpq-dev.
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"""
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import logging
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from typing import Dict, Any, Optional
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from urllib.parse import quote_plus
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from contextlib import contextmanager
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try:
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import psycopg
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from psycopg.rows import dict_row
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PSYCOPG_AVAILABLE = True
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except ImportError as e:
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logging.warning(f"psycopg3 not available: {e}")
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PSYCOPG_AVAILABLE = False
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psycopg = None
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try:
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from langgraph.checkpoint.postgres import PostgresSaver
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LANGGRAPH_POSTGRES_AVAILABLE = True
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except ImportError as e:
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logging.warning(f"LangGraph PostgreSQL checkpoint not available: {e}")
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LANGGRAPH_POSTGRES_AVAILABLE = False
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PostgresSaver = None
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try:
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from langgraph.checkpoint.memory import InMemorySaver
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LANGGRAPH_MEMORY_AVAILABLE = True
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except ImportError as e:
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logging.warning(f"LangGraph memory checkpoint not available: {e}")
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LANGGRAPH_MEMORY_AVAILABLE = False
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InMemorySaver = None
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from ..config import get_config
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logger = logging.getLogger(__name__)
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POSTGRES_AVAILABLE = PSYCOPG_AVAILABLE and LANGGRAPH_POSTGRES_AVAILABLE
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class PostgreSQLCheckpointerWrapper:
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"""
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Wrapper for PostgresSaver that manages the context properly.
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"""
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def __init__(self, conn_string: str):
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if not LANGGRAPH_POSTGRES_AVAILABLE or PostgresSaver is None:
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raise RuntimeError("PostgresSaver not available")
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self.conn_string = conn_string
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self._initialized = False
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def _ensure_setup(self):
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"""Ensure the database schema is set up."""
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if not LANGGRAPH_POSTGRES_AVAILABLE or PostgresSaver is None:
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raise RuntimeError("PostgresSaver not available")
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if not self._initialized:
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with PostgresSaver.from_conn_string(self.conn_string) as saver:
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saver.setup()
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self._initialized = True
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logger.info("PostgreSQL schema initialized")
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@contextmanager
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def get_saver(self):
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"""Get a PostgresSaver instance as context manager."""
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if not LANGGRAPH_POSTGRES_AVAILABLE or PostgresSaver is None:
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raise RuntimeError("PostgresSaver not available")
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self._ensure_setup()
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with PostgresSaver.from_conn_string(self.conn_string) as saver:
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yield saver
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def list(self, config):
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"""List checkpoints."""
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with self.get_saver() as saver:
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return list(saver.list(config))
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def get(self, config):
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"""Get a checkpoint."""
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with self.get_saver() as saver:
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return saver.get(config)
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def get_tuple(self, config):
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"""Get a checkpoint tuple."""
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with self.get_saver() as saver:
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return saver.get_tuple(config)
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def put(self, config, checkpoint, metadata, new_versions):
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"""Put a checkpoint."""
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with self.get_saver() as saver:
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return saver.put(config, checkpoint, metadata, new_versions)
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def put_writes(self, config, writes, task_id):
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"""Put writes."""
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with self.get_saver() as saver:
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return saver.put_writes(config, writes, task_id)
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def get_next_version(self, current, channel):
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"""Get next version."""
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with self.get_saver() as saver:
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return saver.get_next_version(current, channel)
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def delete_thread(self, thread_id):
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"""Delete thread."""
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with self.get_saver() as saver:
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return saver.delete_thread(thread_id)
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# Async methods
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async def alist(self, config):
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"""Async list checkpoints."""
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with self.get_saver() as saver:
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async for item in saver.alist(config):
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yield item
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async def aget(self, config):
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"""Async get a checkpoint."""
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with self.get_saver() as saver:
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# PostgresSaver might not have async version, try sync first
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try:
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return await saver.aget(config)
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except NotImplementedError:
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# Fall back to sync version in a thread
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import asyncio
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return await asyncio.get_event_loop().run_in_executor(
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None, saver.get, config
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)
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async def aget_tuple(self, config):
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"""Async get a checkpoint tuple."""
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with self.get_saver() as saver:
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# PostgresSaver might not have async version, try sync first
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try:
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return await saver.aget_tuple(config)
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except NotImplementedError:
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# Fall back to sync version in a thread
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import asyncio
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return await asyncio.get_event_loop().run_in_executor(
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None, saver.get_tuple, config
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)
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async def aput(self, config, checkpoint, metadata, new_versions):
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"""Async put a checkpoint."""
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with self.get_saver() as saver:
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# PostgresSaver might not have async version, try sync first
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try:
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return await saver.aput(config, checkpoint, metadata, new_versions)
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except NotImplementedError:
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# Fall back to sync version in a thread
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import asyncio
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return await asyncio.get_event_loop().run_in_executor(
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None, saver.put, config, checkpoint, metadata, new_versions
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)
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async def aput_writes(self, config, writes, task_id):
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"""Async put writes."""
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with self.get_saver() as saver:
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# PostgresSaver might not have async version, try sync first
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try:
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return await saver.aput_writes(config, writes, task_id)
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except NotImplementedError:
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# Fall back to sync version in a thread
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import asyncio
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return await asyncio.get_event_loop().run_in_executor(
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None, saver.put_writes, config, writes, task_id
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)
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async def adelete_thread(self, thread_id):
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"""Async delete thread."""
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with self.get_saver() as saver:
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return await saver.adelete_thread(thread_id)
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@property
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def config_specs(self):
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"""Get config specs."""
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with self.get_saver() as saver:
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return saver.config_specs
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@property
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def serde(self):
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"""Get serde."""
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with self.get_saver() as saver:
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return saver.serde
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class PostgreSQLMemoryManager:
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"""
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PostgreSQL-based memory manager using LangGraph's built-in components.
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Falls back to in-memory storage if PostgreSQL is not available.
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"""
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def __init__(self):
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self.config = get_config()
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self.pg_config = self.config.postgresql
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self._checkpointer: Optional[Any] = None
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self._postgres_available = POSTGRES_AVAILABLE
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def _get_connection_string(self) -> str:
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"""Get PostgreSQL connection string."""
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if not self._postgres_available:
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return ""
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# URL encode password to handle special characters
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encoded_password = quote_plus(self.pg_config.password)
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return (
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f"postgresql://{self.pg_config.username}:{encoded_password}@"
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f"{self.pg_config.host}:{self.pg_config.port}/{self.pg_config.database}"
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)
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def _test_connection(self) -> bool:
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"""Test PostgreSQL connection."""
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if not self._postgres_available:
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return False
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if not PSYCOPG_AVAILABLE or psycopg is None:
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return False
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try:
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conn_string = self._get_connection_string()
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with psycopg.connect(conn_string) as conn:
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with conn.cursor() as cur:
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cur.execute("SELECT 1")
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result = cur.fetchone()
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logger.info("PostgreSQL connection test successful")
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return True
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except Exception as e:
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logger.error(f"PostgreSQL connection test failed: {e}")
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return False
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def _setup_ttl_cleanup(self):
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"""Setup TTL cleanup for old records."""
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if not self._postgres_available or not PSYCOPG_AVAILABLE or psycopg is None:
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return
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try:
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conn_string = self._get_connection_string()
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with psycopg.connect(conn_string, autocommit=True) as conn:
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with conn.cursor() as cur:
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# Create a function to clean up old records for LangGraph tables
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# Note: LangGraph tables don't have created_at, so we'll use a different approach
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cleanup_sql = f"""
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CREATE OR REPLACE FUNCTION cleanup_old_checkpoints()
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RETURNS void AS $$
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BEGIN
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-- LangGraph tables don't have created_at columns
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-- We can clean based on checkpoint_id pattern or use a different strategy
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-- For now, just return successfully without actual cleanup
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-- You can implement custom logic based on your requirements
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RAISE NOTICE 'Cleanup function called - custom cleanup logic needed';
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END;
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$$ LANGUAGE plpgsql;
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"""
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cur.execute(cleanup_sql)
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logger.info(f"TTL cleanup function created with {self.pg_config.ttl_days}-day retention")
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except Exception as e:
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logger.warning(f"Failed to setup TTL cleanup (this is optional): {e}")
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def cleanup_old_data(self):
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"""Manually trigger cleanup of old data."""
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if not self._postgres_available or not PSYCOPG_AVAILABLE or psycopg is None:
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return
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try:
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conn_string = self._get_connection_string()
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with psycopg.connect(conn_string, autocommit=True) as conn:
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with conn.cursor() as cur:
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cur.execute("SELECT cleanup_old_checkpoints()")
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logger.info("Manual cleanup of old data completed")
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except Exception as e:
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logger.error(f"Failed to cleanup old data: {e}")
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def get_checkpointer(self):
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"""Get checkpointer for conversation history (PostgreSQL if available, else in-memory)."""
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if self._checkpointer is None:
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if self._postgres_available:
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try:
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# Test connection first
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if not self._test_connection():
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raise Exception("PostgreSQL connection test failed")
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# Setup TTL cleanup function
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self._setup_ttl_cleanup()
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# Create checkpointer wrapper
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conn_string = self._get_connection_string()
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if LANGGRAPH_POSTGRES_AVAILABLE:
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self._checkpointer = PostgreSQLCheckpointerWrapper(conn_string)
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else:
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raise Exception("LangGraph PostgreSQL checkpoint not available")
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logger.info(f"PostgreSQL checkpointer initialized with {self.pg_config.ttl_days}-day TTL")
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except Exception as e:
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logger.error(f"Failed to initialize PostgreSQL checkpointer, falling back to in-memory: {e}")
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if LANGGRAPH_MEMORY_AVAILABLE and InMemorySaver is not None:
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self._checkpointer = InMemorySaver()
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else:
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logger.error("InMemorySaver not available - no checkpointer available")
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self._checkpointer = None
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else:
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logger.info("PostgreSQL not available, using in-memory checkpointer")
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if LANGGRAPH_MEMORY_AVAILABLE and InMemorySaver is not None:
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self._checkpointer = InMemorySaver()
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else:
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logger.error("InMemorySaver not available - no checkpointer available")
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self._checkpointer = None
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return self._checkpointer
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def test_connection(self) -> bool:
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"""Test PostgreSQL connection and return True if successful."""
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return self._test_connection()
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# Global memory manager instance
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_memory_manager: Optional[PostgreSQLMemoryManager] = None
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def get_memory_manager() -> PostgreSQLMemoryManager:
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"""Get global PostgreSQL memory manager instance."""
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global _memory_manager
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if _memory_manager is None:
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_memory_manager = PostgreSQLMemoryManager()
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return _memory_manager
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def get_checkpointer():
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"""Get checkpointer for conversation history."""
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return get_memory_manager().get_checkpointer()
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