Enrich README.md for postgres usage, make some change to cater python version<12

README.md

@@ -360,6 +360,7 @@ see test_neo4j.py for a working example.
 ### Using PostgreSQL for Storage
 For production level scenarios you will most likely want to leverage an enterprise solution. PostgreSQL can provide a one-stop solution for you as KV store, VectorDB (pgvector) and GraphDB (apache AGE).
 * PostgreSQL is lightweight,the whole binary distribution including all necessary plugins can be zipped to 40MB: Ref to [Windows Release](https://github.com/ShanGor/apache-age-windows/releases/tag/PG17%2Fv1.5.0-rc0) as it is easy to install for Linux/Mac.
+* If you prefer docker, please start with this image if you are a beginner to avoid hiccups (DO read the overview): https://hub.docker.com/r/shangor/postgres-for-rag
 * How to start? Ref to: [examples/lightrag_zhipu_postgres_demo.py](https://github.com/HKUDS/LightRAG/blob/main/examples/lightrag_zhipu_postgres_demo.py)
 * Create index for AGE example: (Change below `dickens` to your graph name if necessary)
   ```

examples/copy_postgres_llm_cache_to_json.py

@@ -0,0 +1,66 @@
+import asyncio
+import logging
+import os
+from dotenv import load_dotenv
+
+from lightrag.kg.postgres_impl import PostgreSQLDB, PGKVStorage
+from lightrag.storage import JsonKVStorage
+
+load_dotenv()
+ROOT_DIR = os.environ.get("ROOT_DIR")
+WORKING_DIR = f"{ROOT_DIR}/dickens-pg"
+
+logging.basicConfig(format="%(levelname)s:%(message)s", level=logging.INFO)
+
+if not os.path.exists(WORKING_DIR):
+    os.mkdir(WORKING_DIR)
+
+# AGE
+os.environ["AGE_GRAPH_NAME"] = "chinese"
+
+postgres_db = PostgreSQLDB(
+    config={
+        "host": "localhost",
+        "port": 15432,
+        "user": "rag",
+        "password": "rag",
+        "database": "r1",
+    }
+)
+
+
+async def main():
+    await postgres_db.initdb()
+
+    from_llm_response_cache = PGKVStorage(
+        namespace="llm_response_cache",
+        global_config={"embedding_batch_num": 6},
+        embedding_func=None,
+        db=postgres_db,
+    )
+
+    to_llm_response_cache = JsonKVStorage(
+        namespace="llm_response_cache",
+        global_config={"working_dir": WORKING_DIR},
+        embedding_func=None,
+    )
+
+    kv = {}
+    for c_id in await from_llm_response_cache.all_keys():
+        print(f"Copying {c_id}")
+        workspace = c_id["workspace"]
+        mode = c_id["mode"]
+        _id = c_id["id"]
+        postgres_db.workspace = workspace
+        obj = await from_llm_response_cache.get_by_mode_and_id(mode, _id)
+        if mode not in kv:
+            kv[mode] = {}
+        kv[mode][_id] = obj[_id]
+        print(f"Object {obj}")
+    await to_llm_response_cache.upsert(kv)
+    await to_llm_response_cache.index_done_callback()
+    print("Mission accomplished!")
+
+
+if __name__ == "__main__":
+    asyncio.run(main())

lightrag/kg/postgres_impl.py

@@ -231,6 +231,16 @@ class PGKVStorage(BaseKVStorage):
         else:
             return None
 
+    async def all_keys(self) -> list[dict]:
+        if "llm_response_cache" == self.namespace:
+            sql = "select workspace,mode,id from lightrag_llm_cache"
+            res = await self.db.query(sql, multirows=True)
+            return res
+        else:
+            logger.error(
+                f"all_keys is only implemented for llm_response_cache, not for {self.namespace}"
+            )
+
     async def filter_keys(self, keys: List[str]) -> Set[str]:
         """Filter out duplicated content"""
         sql = SQL_TEMPLATES["filter_keys"].format(
@@ -412,7 +422,10 @@ class PGDocStatusStorage(DocStatusStorage):
 
     async def filter_keys(self, data: list[str]) -> set[str]:
         """Return keys that don't exist in storage"""
-        sql = f"SELECT id FROM LIGHTRAG_DOC_STATUS WHERE workspace=$1 AND id IN ({",".join([f"'{_id}'" for _id in data])})"
+        keys = ",".join([f"'{_id}'" for _id in data])
+        sql = (
+            f"SELECT id FROM LIGHTRAG_DOC_STATUS WHERE workspace=$1 AND id IN ({keys})"
+        )
         result = await self.db.query(sql, {"workspace": self.db.workspace}, True)
         # The result is like [{'id': 'id1'}, {'id': 'id2'}, ...].
         if result is None: