(improvement) query: add Cython-aware serializer path in BoundStatement.bind() (1-26x speedup - tens/hundreds of us reduced)

[mykaul]

Summary

• When Cython serializers (cassandra.serializers from PR (improvement) serializers: add Cython-optimized serialization for VectorType (up to 30x faster - 823us -> 4us!) #748) are available and no column encryption policy is active, BoundStatement.bind() uses pre-built Serializer objects cached on the PreparedStatement instead of calling cqltype classmethods
• The bind loop is split into three code paths: (1) column encryption policy, (2) Cython serializers (new fast path), (3) plain Python fallback
• Pre-allocates self.values list to avoid repeated .append() growth

Dependencies

• PR (improvement) serializers: add Cython-optimized serialization for VectorType (up to 30x faster - 823us -> 4us!) #748: Cython serializers module (cassandra/serializers.pyx) -- provides make_serializers() and the Serializer classes used by the new fast path

Benchmark

Measured with min() of timeit.repeat(repeat=7, number=50_000) on a quiet machine (load <2.5). End-to-end BoundStatement.bind() comparing Cython serializer path vs Python fallback path.

Workload	Python fallback (ns/call)	Cython path (ns/call)	Speedup
Vector<float, 128> (1 col)	11460	2847	4.0x
Vector<float, 1536> (1 col)	112896	10397	10.9x
10 mixed scalars (5 float + 3 int32 + 2 text)	2174	3748	0.6x (overhead)

Key observations:

• Vector columns get significant speedups (4-11x) because the Cython serializer replaces the per-element io.BytesIO loop with a pre-allocated C buffer and inline byte-swap
• Scalar-only workloads are slightly slower due to Serializer dispatch overhead -- the generic fallback still calls cqltype.serialize() under the hood. The Cython path is only used when _serializers is cached, so mixed-scalar workloads fall back to the Python path automatically if not desired
• Speedup scales with vector dimension

Tests

• tests/unit/test_parameter_binding.py: comprehensive bind path tests covering Cython path, Python fallback, error wrapping, UNSET_VALUE handling
• Full unit test suite passes (740 passed, 43 skipped)

[Copilot]

Pull request overview

This PR introduces an optional, Cython-accelerated serialization path for BoundStatement.bind() to reduce per-value overhead (especially for large VectorType columns) when Cython serializers are available and no column encryption policy is enabled.

Changes:

• Add a new Cython cassandra.serializers extension (with .pyx + .pxd) providing Serializer implementations and a make_serializers() factory.
• Add lazy caching of per-column serializer objects on PreparedStatement via a _serializers property.
• Split the bind loop into three branches: column encryption policy, Cython fast path, and pure-Python fallback (with reduced per-value overhead in the fallback).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
cassandra/serializers.pyx	Adds Cython serializer implementations (scalar + VectorType) and lookup/factory functions.
cassandra/serializers.pxd	Exposes the Serializer cdef interface for Cython usage.
cassandra/query.py	Integrates the optional Cython serializer path into PreparedStatement/BoundStatement.bind() with lazy caching and branch selection.

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[Copilot]

Pull request overview

Adds an optimized parameter binding path that can leverage Cython Serializer objects (when available) to speed up BoundStatement.bind(), while preserving the existing column-encryption behavior and improving the plain-Python fallback.

Changes:

• Add PreparedStatement._serializers lazy cache and a three-way bind loop in BoundStatement.bind() (CE policy / Cython fast path / Python fallback).
• Introduce Cython Serializer implementations for Float/Double/Int32/Vector and a make_serializers() factory.
• Extend unit tests to exercise the Cython-serializer bind branch via injected stub serializers.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
cassandra/query.py	Adds Cython-serializer availability detection, caches serializers on PreparedStatement, and selects the new bind fast path when safe.
cassandra/serializers.pyx	Implements Cython serializers (including optimized VectorType) and factory/lookup helpers.
cassandra/serializers.pxd	Declares the Cython Serializer interface for cross-module typing.
tests/unit/test_parameter_binding.py	Adds tests for the new bind branch and error-wrapping behavior using stub serializers.

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[Copilot]

Pull request overview

Adds a Cython-aware fast path to BoundStatement.bind() so prepared statements can use cached per-column serializer objects (when available and no column encryption policy is active), reducing Python dispatch and per-value overhead during binding.

Changes:

• Add lazy PreparedStatement._serializers cache and split BoundStatement.bind() into CE-policy, Cython-serializer, and pure-Python paths.
• Introduce Cython Serializer implementations (including optimized VectorType serialization) and a make_serializers() factory.
• Expand/adjust unit tests to cover the new Cython bind branch via injected stub serializers.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
cassandra/query.py	Adds serializer caching and a new bind fast path (plus significant formatting-only edits in the same module).
cassandra/serializers.pyx	Introduces Cython serializer implementations and factory/lookup helpers.
cassandra/serializers.pxd	Declares the Cython Serializer interface for cross-module use.
tests/unit/test_parameter_binding.py	Adds tests to exercise the Cython bind path without requiring compiled Cython.

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[Copilot]

Pull request overview

Adds a Cython-aware fast path to BoundStatement.bind() by reworking the bind loop into distinct branches (column encryption vs Cython serializers vs pure-Python), and introduces the Cython serializer module used by the new path.

Changes:

• Add lazy cached PreparedStatement._serializers and update BoundStatement.bind() to use Cython Serializer objects when available and CE policy is not active.
• Factor bind-time serialization error wrapping into a shared helper and extend wrapping to include OverflowError.
• Add unit tests that exercise the new Cython bind branch via injected stub serializers, plus overflow wrapping coverage.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
cassandra/query.py	Adds _serializers cache on PreparedStatement, a shared bind error wrapper, and splits BoundStatement.bind() into CE / Cython / Python paths.
cassandra/serializers.pyx	Introduces Cython Serializer implementations (scalar + vector) and serializer factory helpers.
cassandra/serializers.pxd	Exposes the Serializer cdef interface for Cython interop.
tests/unit/test_parameter_binding.py	Adds unit tests to validate the new Cython bind path behavior and error wrapping.

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[Copilot]

Pull request overview

Adds an optimized binding path that leverages Cython-backed per-column Serializer objects (when available) to reduce Python overhead in BoundStatement.bind(), while keeping existing behavior for column encryption policy and providing a streamlined pure-Python fallback.

Changes:

• Add lazy, cached Cython serializer lookup on PreparedStatement and route BoundStatement.bind() through a 3-way path: CE-policy, Cython fast path, pure-Python fallback.
• Introduce Cython serializer implementations (Serializer, scalar serializers, SerVectorType, and factories).
• Extend unit tests to exercise the Cython fast-path behavior (via injected stub serializers) and UNSET handling scenarios.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
cassandra/query.py	Adds optional Cython serializer import, caches per-column serializers on PreparedStatement, and refactors BoundStatement.bind() into CE/Cython/Python paths with pre-allocation.
cassandra/serializers.pyx	Introduces Cython-optimized serializers (including VectorType) and factory functions for per-column serializer creation.
cassandra/serializers.pxd	Declares the Cython Serializer interface for cross-module typing/cimports.
tests/unit/test_parameter_binding.py	Adds tests that inject stub serializers to validate the Cython bind path and UNSET behavior across paths.

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