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### **Summary** Closes #3212 Extends the Python `lit()` helper to natively support three additional types (`date`, `datetime`, and `Decimal`) and implements reflexive operators for the `Expr` class. This implementation specifically addresses the blocking feedback regarding precision loss, CI discovery, and query engine limitations: * **Logic Refactoring**: Simplified `lit()` by combining `date` and `datetime` normalization into ISO-8601 strings, ensuring stable SQL parsing across different engine locales. * **Precision Preservation**: `decimal.Decimal` objects are now passed as high-precision strings to the Rust bridge, bypassing intermediate float conversions and preserving full 128-bit decimal precision for DataFusion. * **Averted CI Failures**: Temporarily deferred `bytes` literal support to a future PR to resolve a known DataFusion `expr_to_sql` limitation that was crashing the `Doctest` runner. * **Reflexive Operators**: Added support for "literal-first" arithmetic and logical operations (e.g., `10 + col('a')` or `True & col('active')`). Redundant reflexive comparisons (e.g., `__rlt__`) were pruned as Python's data model handles them automatically. * **Integration Verification**: Added dedicated integration tests in the official test directory to ensure the query engine correctly handles the new types and preserves bit-perfect fidelity. ### **Changes** #### [python/python/lancedb/expr.py](file:///c:/Users/Laksh/Documents/lancedb/python/python/lancedb/expr.py) * Updated `lit()` to handle `date`, `datetime`, and `Decimal` natively. * Implemented reflexive operators (`__radd__`, `__rand__`, `__rmul__`, etc.) to support literals on the left-hand side. * Removed the problematic `bytes` doctest example and `lit()` type support to unblock CI. #### [python/src/expr.rs](file:///c:/Users/Laksh/Documents/lancedb/python/src/expr.rs) * Modified the Rust FFI bridge to extract `Decimal` objects as strings. * Ensured the `expr_lit` handler is ready to receive normalized temporal strings. * Consolidated imports and added missing operator documentation. #### [python/python/lancedb/_lancedb.pyi](file:///c:/Users/Laksh/Documents/lancedb/python/python/lancedb/_lancedb.pyi) * Updated type stubs for `expr_lit` to include `Any` (allowing for `Decimal`). ### **Testing** Added several new advanced test cases in [python/python/tests/test_expr.py](file:///c:/Users/Laksh/Documents/lancedb/python/python/tests/test_expr.py) covering: * **High-precision Decimal preservation**: Verified against 128-bit boundaries with a "one point off" test case (`1.234567890123456789 < 1.234567890123456790`). * **Reflexive operator positioning**: Verified successful query construction with literals on the left. * **Timezone-aware normalization**: Confirmed stable behavior for `datetime` objects. * **Integration Testing**: Confirmed Date32 and Decimal columns return the correct Python types and values from the engine during `.to_arrow()` calls. --------- Co-authored-by: Will Jones <willjones127@gmail.com> Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
LanceDB Python SDK
A Python library for LanceDB.
Installation
pip install lancedb
Preview Releases
Stable releases are created about every 2 weeks. For the latest features and bug fixes, you can install the preview release. These releases receive the same level of testing as stable releases, but are not guaranteed to be available for more than 6 months after they are released. Once your application is stable, we recommend switching to stable releases.
pip install --pre --extra-index-url https://pypi.fury.io/lancedb/ lancedb
Usage
Basic Example
import lancedb
db = lancedb.connect('<PATH_TO_LANCEDB_DATASET>')
table = db.open_table('my_table')
results = table.search([0.1, 0.3]).limit(20).to_list()
print(results)
Development
See CONTRIBUTING.md for information on how to contribute to LanceDB.