Make PostgreSQL statement_cache_size configuration optional

• Remove forced int conversion
• Allow None values for cache size
• Add conditional parameter setting

lightrag/kg/postgres_impl.py

@@ -77,8 +77,8 @@ class PostgreSQLDB:
         # Server settings
         self.server_settings = config.get("server_settings")
 
-        # Statement LRU cache size
-        self.statement_cache_size = int(config.get("statement_cache_size"))
+        # Statement LRU cache size (keep as-is, allow None for optional configuration)
+        self.statement_cache_size = config.get("statement_cache_size")
 
         if self.user is None or self.password is None or self.database is None:
             raise ValueError("Missing database user, password, or database")
@@ -164,12 +164,16 @@ class PostgreSQLDB:
                 "port": self.port,
                 "min_size": 1,
                 "max_size": self.max,
-                "statement_cache_size": self.statement_cache_size,
             }
 
-            logger.info(
-                f"PostgreSQL, statement LRU cache size set as: {self.statement_cache_size}"
-            )
+            # Only add statement_cache_size if it's configured
+            if self.statement_cache_size is not None:
+                connection_params["statement_cache_size"] = int(
+                    self.statement_cache_size
+                )
+                logger.info(
+                    f"PostgreSQL, statement LRU cache size set as: {self.statement_cache_size}"
+                )
 
             # Add SSL configuration if provided
             ssl_context = self._create_ssl_context()