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Philippe PRADOS 8250c177de community[minor]: Add native async support to SQLChatMessageHistory (#22065) ... # package community: Fix SQLChatMessageHistory ## Description Here is a rewrite of `SQLChatMessageHistory` to properly implement the asynchronous approach. The code circumvents [issue 22021](https://github.com/langchain-ai/langchain/issues/22021) by accepting a synchronous call to `def add_messages()` in an asynchronous scenario. This bypasses the bug. For the same reasons as in [PR 22](https://github.com/langchain-ai/langchain-postgres/pull/32) of `langchain-postgres`, we use a lazy strategy for table creation. Indeed, the promise of the constructor cannot be fulfilled without this. It is not possible to invoke a synchronous call in a constructor. We compensate for this by waiting for the next asynchronous method call to create the table. The goal of the `PostgresChatMessageHistory` class (in `langchain-postgres`) is, among other things, to be able to recycle database connections. The implementation of the class is problematic, as we have demonstrated in [issue 22021](https://github.com/langchain-ai/langchain/issues/22021). Our new implementation of `SQLChatMessageHistory` achieves this by using a singleton of type (`Async`)`Engine` for the database connection. The connection pool is managed by this singleton, and the code is then reentrant. We also accept the type `str` (optionally complemented by `async_mode`. I know you don't like this much, but it's the only way to allow an asynchronous connection string). In order to unify the different classes handling database connections, we have renamed `connection_string` to `connection`, and `Session` to `session_maker`. Now, a single transaction is used to add a list of messages. Thus, a crash during this write operation will not leave the database in an unstable state with a partially added message list. This makes the code resilient. We believe that the `PostgresChatMessageHistory` class is no longer necessary and can be replaced by: ``` PostgresChatMessageHistory = SQLChatMessageHistory ``` This also fixes the bug. ## Issue - [issue 22021](https://github.com/langchain-ai/langchain/issues/22021) - Bug in _exit_history() - Bugs in PostgresChatMessageHistory and sync usage - Bugs in PostgresChatMessageHistory and async usage - [issue 36](https://github.com/langchain-ai/langchain-postgres/issues/36) ## Twitter handle: pprados ## Tests - libs/community/tests/unit_tests/chat_message_histories/test_sql.py (add async test) @baskaryan, @eyurtsev or @hwchase17 can you check this PR ? And, I've been waiting a long time for validation from other PRs. Can you take a look? - [PR 32](https://github.com/langchain-ai/langchain-postgres/pull/32) - [PR 15575](https://github.com/langchain-ai/langchain/pull/15575) - [PR 13200](https://github.com/langchain-ai/langchain/pull/13200) --------- Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>		3 months ago
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__init__.py	community[minor]: Add Zep Cloud components + docs + examples (#21671)	3 months ago
astradb.py	(all): update removal in deprecation warnings from 0.2 to 0.3 (#21265)	4 months ago
cassandra.py	community[minor]: Add async methods to CassandraChatMessageHistory (#21975)	4 months ago
cosmos_db.py	infra: rm unused # noqa violations (#22049)	4 months ago
dynamodb.py	community[patch]: history size support for DynamoDBChatMessageHistory (#16794)	5 months ago
elasticsearch.py	community[patch]: mypy ignore fix (#18483)	5 months ago
file.py	core[patch],community[patch]: Move file chat history back to community (#20834)	5 months ago
firestore.py	community[major], core[patch], langchain[patch], experimental[patch]: Create langchain-community (#14463)	9 months ago
in_memory.py	core[minor],langchain[patch],community[patch]: Move InMemory and File implementations of Chat History to core (#20752)	5 months ago
momento.py	community[major], core[patch], langchain[patch], experimental[patch]: Create langchain-community (#14463)	9 months ago
mongodb.py	(all): update removal in deprecation warnings from 0.2 to 0.3 (#21265)	4 months ago
neo4j.py	community[patch]: chat message history mypy fixes #17048 (#20114)	4 months ago
postgres.py	community[patch]: Add deprecation warnings to postgres implementation (#20222)	5 months ago
redis.py	community[patch]: chat message history mypy fixes #17048 (#20114)	4 months ago
rocksetdb.py	infra: add print rule to ruff (#16221)	7 months ago
singlestoredb.py	community[major], core[patch], langchain[patch], experimental[patch]: Create langchain-community (#14463)	9 months ago
sql.py	community[minor]: Add native async support to SQLChatMessageHistory (#22065)	3 months ago
streamlit.py	community: Fix bug with StreamlitChatMessageHistory (#18834)	6 months ago
tidb.py	community[patch]: chat message history mypy fixes (#17059)	7 months ago
upstash_redis.py	community[major], core[patch], langchain[patch], experimental[patch]: Create langchain-community (#14463)	9 months ago
xata.py	multiple: Remove unnecessary Ruff suppression comments (#21050)	4 months ago
zep.py	docs: community docstring updates (#21040)	4 months ago
zep_cloud.py	community[minor]: Add Zep Cloud components + docs + examples (#21671)	3 months ago