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fix(python): return the session supplied to LanceDBConnection - #4433
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Xuanwo merged 1 commit intoOct 22, 2026
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LanceDBConnection.session read AsyncConnection.session, but AsyncConnection has no session attribute, so access raised AttributeError. Store the session passed to the constructor and return that object. Assisted by Cursor (Grok).
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Returning the caller-supplied session fixes the attribute failure and keeps property inspection synchronous for direct and reconstructed connections. Callers that retain closed connection wrappers should account for the supplied session’s cache lifetime.
| # The native connection does not expose the Python Session wrapper. | ||
| # Keep the object supplied by the caller so this property stays | ||
| # synchronous for debugger inspection. | ||
| self._session = session |
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A closed connection wrapper now retains its supplied session’s caches. The new strong reference survives close(), which only closes _conn. Passing a temporary Session and retaining the closed connection can therefore keep populated caches alive up to their configured limits.
This is non-blocking because dropping the closed wrapper releases its session reference. Clearing _session during close() is an alternative if explicit connection cleanup should release that reference.
Reproducer
import gc
import tempfile
import lancedb
with tempfile.TemporaryDirectory() as uri:
db = lancedb.connect(
uri,
session=lancedb.Session(
index_cache_size_bytes=1024 * 1024,
metadata_cache_size_bytes=512 * 1024,
),
)
table = db.create_table("test", [{"id": i} for i in range(100)])
table.to_arrow()
del table
gc.collect()
before = db.session.size_bytes
db.close()
gc.collect()
assert not db.is_open()
print(before, db.session.size_bytes)On this revision, the connection is closed but this prints 5133 5133: the populated session cache is still retained.
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Fixes #4400. Sync remote connections fail on `uri`, `len(db)`, and `name in db`, and remote tables lack `namespace`, `id`, and `replace_field_metadata`. Share the paginated connection helpers and table identifier contract through the base classes, and delegate remote metadata replacement to the existing async implementation. Unsupported remote session and read-consistency properties raise explicit `NotImplementedError`s. Reconciled with main at `3dd57978`, including the synchronous method signatures from #4498. The local session fix has already landed in #4433, so this PR preserves its supplied-session-or-None contract and adds no Rust/PyO3 session access. Namespace connections retain their writable properties. Existing custom `Table` subclasses remain instantiable: `namespace` defaults to a fresh empty list, and deprecated `replace_field_metadata` delegates to `update_field_metadata` with `replace=True` while retaining its `None` return. Native and remote overrides are preserved. Regression tests instantiate an old-style subclass through normal ABC class creation and verify identifiers, independent namespace lists, deprecation, and exact metadata delegation. Historical validation at `03c43f7b` before the latest main integration and subclass compatibility repair, Ubuntu x86-64, Python 3.12.13: - Rebuilt the native extension with the repository `ci` profile and locked Python dependencies. - 273 tests passed across `test_sync_api_parity.py`, `test_db.py`, `test_remote_db.py`, and `test_session.py`. - 84 namespace and catalog compatibility tests passed (357 tests total). - Python SDK lint and formatting pass (158 files); changed-file checks and `git diff --check` pass. - Repository-wide lint/format checks report existing issues in unchanged `docs/web-tests` files (49 lint findings and 11 formatting files). These are outside this patch. Remote tests use the existing HTTP fixtures through the rebuilt native client; the original aarch64 server deployment was not recreated. Validation after merging main `3dd57978` and the compatibility repair (macOS ARM64, uv-managed Python 3.12.12, rebuilt editable native extension): - 60 focused parity, signature, and error-contract tests passed. - 381 database, remote, session, namespace, catalog, and sync parity tests passed; 2 platform-dependent tests skipped. - The two new subclass regressions fail against the pre-repair implementation with the expected abstract-member instantiation error, then pass with the repair. - Python SDK Ruff lint/format passes (167 files); repository-wide findings remain confined to unchanged docs/web-tests (49 lint findings, 11 formatting files). --------- Co-authored-by: Xuanwo <[email protected]>
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LanceDBConnection.session read AsyncConnection.session, but AsyncConnection has no session attribute, so access raised AttributeError. Store the session passed to the constructor and return that object.
Assisted by Cursor (Grok).