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[Bug]: Internal server error when filtering with created_at #959

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[Bug]: Internal server error when filtering with created_at#959
Bug
Assignees
o-love

Description

@mwqgithub
mwqgithub
opened on Jan 19, 2026

Describe the bug

When filtering memories with creation time, memmachine reports an internal server error.
Here's the server log:

INFO:     172.19.0.1:56762 - "POST /api/v2/memories/search HTTP/1.1" 500 Internal Server Error
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 526, in _prepare_and_execute
    prepared_stmt, attributes = await adapt_connection._prepare(
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 773, in _prepare
    prepared_stmt = await self._connection.prepare(
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/asyncpg/connection.py", line 638, in prepare
    return await self._prepare(
           ^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/asyncpg/connection.py", line 657, in _prepare
    stmt = await self._get_statement(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/asyncpg/connection.py", line 443, in _get_statement
    statement = await self._protocol.prepare(
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "asyncpg/protocol/protocol.pyx", line 165, in prepare
asyncpg.exceptions.UndefinedFunctionError: operator does not exist: timestamp with time zone < character varying
HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1967, in _exec_single_context
    self.dialect.do_execute(
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/default.py", line 951, in do_execute
    cursor.execute(statement, parameters)
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 585, in execute
    self._adapt_connection.await_(
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 132, in await_only
    return current.parent.switch(awaitable)  # type: ignore[no-any-return,attr-defined] # noqa: E501
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 196, in greenlet_spawn
    value = await result
            ^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 563, in _prepare_and_execute
    self._handle_exception(error)
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 513, in _handle_exception
    self._adapt_connection._handle_exception(error)
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 797, in _handle_exception
    raise translated_error from error
sqlalchemy.dialects.postgresql.asyncpg.AsyncAdapt_asyncpg_dbapi.ProgrammingError: <class 'asyncpg.exceptions.UndefinedFunctionError'>: operator does not exist: timestamp with time zone < character varying
HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/app/.venv/lib/python3.12/site-packages/uvicorn/protocols/http/h11_impl.py", line 403, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/uvicorn/middleware/proxy_headers.py", line 60, in __call__
    return await self.app(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/fastapi/applications.py", line 1139, in __call__
    await super().__call__(scope, receive, send)
  File "/app/.venv/lib/python3.12/site-packages/starlette/applications.py", line 107, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/base.py", line 191, in __call__
    with recv_stream, send_stream, collapse_excgroups():
                                   ^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/contextlib.py", line 158, in __exit__
    self.gen.throw(value)
  File "/app/.venv/lib/python3.12/site-packages/starlette/_utils.py", line 85, in collapse_excgroups
    raise exc
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/base.py", line 193, in __call__
    response = await self.dispatch_func(request, call_next)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/memmachine/server/middleware.py", line 75, in dispatch
    response = await call_next(request)
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/base.py", line 168, in call_next
    raise app_exc from app_exc.__cause__ or app_exc.__context__
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/base.py", line 144, in coro
    await self.app(scope, receive_or_disconnect, send_no_error)
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/base.py", line 191, in __call__
    with recv_stream, send_stream, collapse_excgroups():
                                   ^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/contextlib.py", line 158, in __exit__
    self.gen.throw(value)
  File "/app/.venv/lib/python3.12/site-packages/starlette/_utils.py", line 85, in collapse_excgroups
    raise exc
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/base.py", line 193, in __call__
    response = await self.dispatch_func(request, call_next)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/memmachine/server/middleware.py", line 26, in dispatch
    response = await call_next(request)
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/base.py", line 168, in call_next
    raise app_exc from app_exc.__cause__ or app_exc.__context__
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/base.py", line 144, in coro
    await self.app(scope, receive_or_disconnect, send_no_error)
  File "/app/.venv/lib/python3.12/site-packages/starlette/middleware/exceptions.py", line 63, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/app/.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/app/.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/app/.venv/lib/python3.12/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "/app/.venv/lib/python3.12/site-packages/starlette/routing.py", line 716, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/app/.venv/lib/python3.12/site-packages/starlette/routing.py", line 736, in app
    await route.handle(scope, receive, send)
  File "/app/.venv/lib/python3.12/site-packages/starlette/routing.py", line 290, in handle
    await self.app(scope, receive, send)
  File "/app/.venv/lib/python3.12/site-packages/fastapi/routing.py", line 119, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/app/.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/app/.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/app/.venv/lib/python3.12/site-packages/fastapi/routing.py", line 105, in app
    response = await f(request)
               ^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/fastapi/routing.py", line 385, in app
    raw_response = await run_endpoint_function(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/fastapi/routing.py", line 284, in run_endpoint_function
    return await dependant.call(**values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/memmachine/server/api_v2/router.py", line 301, in search_memories
    return await _search_target_memories(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/memmachine/server/api_v2/service.py", line 87, in _search_target_memories
    results = await memmachine.query_search(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/memmachine/main/memmachine.py", line 374, in query_search
    semantic_memory=await semantic_task if semantic_task else None,
                    ^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/memmachine/semantic_memory/semantic_session_manager.py", line 174, in search
    return await self._semantic_service.search(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/memmachine/semantic_memory/semantic_memory.py", line 104, in search
    return await self._semantic_storage.get_feature_set(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/memmachine/semantic_memory/storage/sqlalchemy_pgvector_semantic.py", line 353, in get_feature_set
    result = await session.execute(stmt)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/ext/asyncio/session.py", line 449, in execute
    result = await greenlet_spawn(
             ^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 201, in greenlet_spawn
    result = context.throw(*sys.exc_info())
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/orm/session.py", line 2351, in execute
    return self._execute_internal(
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/orm/session.py", line 2249, in _execute_internal
    result: Result[Any] = compile_state_cls.orm_execute_statement(
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/orm/context.py", line 306, in orm_execute_statement
    result = conn.execute(
             ^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1419, in execute
    return meth(
           ^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/sql/elements.py", line 526, in _execute_on_connection
    return connection._execute_clauseelement(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1641, in _execute_clauseelement
    ret = self._execute_context(
          ^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1846, in _execute_context
    return self._exec_single_context(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1986, in _exec_single_context
    self._handle_dbapi_exception(
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 2355, in _handle_dbapi_exception
    raise sqlalchemy_exception.with_traceback(exc_info[2]) from e
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1967, in _exec_single_context
    self.dialect.do_execute(
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/engine/default.py", line 951, in do_execute
    cursor.execute(statement, parameters)
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 585, in execute
    self._adapt_connection.await_(
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 132, in await_only
    return current.parent.switch(awaitable)  # type: ignore[no-any-return,attr-defined] # noqa: E501
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 196, in greenlet_spawn
    value = await result
            ^^^^^^^^^^^^
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 563, in _prepare_and_execute
    self._handle_exception(error)
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 513, in _handle_exception
    self._adapt_connection._handle_exception(error)
  File "/app/.venv/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 797, in _handle_exception
    raise translated_error from error
sqlalchemy.exc.ProgrammingError: (sqlalchemy.dialects.postgresql.asyncpg.ProgrammingError) <class 'asyncpg.exceptions.UndefinedFunctionError'>: operator does not exist: timestamp with time zone < character varying
HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
[SQL: SELECT feature.id, feature.set_id, feature.semantic_category_id, feature.tag_id, feature.feature, feature.value, feature.created_at, feature.updated_at, feature.embedding, feature.metadata 
FROM feature 
WHERE feature.set_id IN ($5::VARCHAR) AND feature.created_at < $1::VARCHAR ORDER BY (feature.embedding <=> $2) ASC 
 LIMIT $3::INTEGER OFFSET $4::INTEGER]
[parameters: ('2026-01-19T01:56:41.513342Z', '[0.02199697308242321,0.03521528095006943,0.04069880396127701,0.01604810729622841,0.034108515828847885,-0.007464381866157055,-0.0026725882198661566,0. ... (32391 characters truncated) ... 02422622637823224,-0.025455618277192116,0.0025028004311025143,-0.0019352682866156101,-0.008042918518185616,0.01651345193386078,-0.011683926917612553]', 100, 0, 'mem_session_test_org/test_project')]
(Background on this error at: https://sqlalche.me/e/20/f405)

Steps to reproduce

root@iZj6c1jorqijanhc9iulkgZ:~/MemMachine# curl -X POST "http://127.0.0.1:8080/api/v2/memories/search"   -H "Content-Type: application/json"   -d @- <<'JSON'
{
  "org_id": "test_org",
  "project_id": "test_project",
  "filter": "created_at<'2026-01-19T01:56:41.513342Z'",
  "query": "",
  "top_k": 100
}
JSON
Internal Server Errorroot@iZj6c1jorqijanhc9iulkgZ:~/MemMachine#

Expected behavior

Expect memories can be filtered with creation time.

Environment

  • OS: ubuntu24
  • Memmachine version: be2264b

Additional context

No response

Activity

  1. mwqgithub
    added the
    Bug
    issue type on Jan 19, 2026
  2. malatewang
    assigned
    o-love
    on Jan 19, 2026
  3. o-love
    added 2 commits that reference this issue on Jan 20, 2026

    [GH-959] Add datetime filter expr support

    1c86ff5

    [GH-959] Add datetime filter expr support

    aa4342f

  4. o-love commented on Jan 20, 2026

    @o-love
    o-love
    on Jan 20, 2026
    Contributor

    Cause: Datetime parsing isn't part of the filter expressions. So our filter parser never converts these striings to datetime.

    The filter expression from the issue would have worked on Neo4j(so by extension episodic) because neo4j takes in iso strings as its datetime argument.
    But it fails on all other storage backends.

    I've added in a date keyword in #960
    With that the filter expression would look like created_at < date('2026-01-19T01:56:41.513342Z')

  5. o-love
    added 3 commits that reference this issue on Jan 20, 2026

    [GH-959] Add datetime filter expr support

    54380e0

    [GH-959] Add datetime filter expr support

    8e58a15

    [GH-959] Add datetime filter expr support

    c0d7a88
  6. o-love
    added 4 commits that reference this issue on Jan 27, 2026

    [GH-959] Add datetime filter expr support

    87888ec

    [GH-959] Add datetime filter expr support

    0685593

    [GH-959] Add datetime filter expr support

    a03def6

    [GH-959] Add datetime filter expr support (#960)

    cff6993

  7. o-love commented on Jan 28, 2026

    @o-love
    o-love
    on Jan 28, 2026
    Contributor

    Fixed by #960

  8. o-love
    closed this as completedon Jan 28, 2026
  9. SarahScargall
    added a commit that references this issue on Jan 29, 2026

    [MemMachineGH-959] Add datetime filter expr support (MemMachine#960)

    073f42b
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