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Fix transactions not being committed #60

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Fix transactions not being committed #60

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2 changes: 2 additions & 0 deletions langchain_postgres/chat_message_histories.py
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Original file line number Diff line number Diff line change
Expand Up @@ -320,6 +320,7 @@ def get_messages(self) -> List[BaseMessage]:
with self._connection.cursor() as cursor:
cursor.execute(query, {"session_id": self._session_id})
items = [record[0] for record in cursor.fetchall()]
self._connection.commit()
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Does a transaction need to be committed here? There's no mutation that's done in get_messages

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@LeiTi34 LeiTi34 Jun 5, 2024 •
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Yes, the transaction is still created and never commits, which can block other operations.

See the first code example in the docs.
There conn.close() closes the transaction.

Another option would be to use Autocommit transactions.

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@LeiTi34 LeiTi34 Jun 11, 2024 •
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While doing some research I stumbled on this article, which describes some implications of having not committed transactions.

Basically, it avoids VACUUM marking rows as eligible for reuse, as long as the connection is open.

That means, that if someone builds an application that is rarely restarted using this library, it can grow the size of the DB drastically.


messages = messages_from_dict(items)
return messages
Expand All @@ -336,6 +337,7 @@ async def aget_messages(self) -> List[BaseMessage]:
async with self._aconnection.cursor() as cursor:
await cursor.execute(query, {"session_id": self._session_id})
items = [record[0] for record in await cursor.fetchall()]
await self._aconnection.commit()

messages = messages_from_dict(items)
return messages
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