FEAT: varbinarymax streaming support in execute()

[gargsaumya]

Work Item / Issue Reference

AB#33395

GitHub Issue: #<ISSUE_NUMBER>

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Summary

This pull request adds support for streaming large binary parameters (bytes and bytearray) to SQL Server using VARBINARY(MAX), removing the previous limitation that prevented inserting binary data larger than 8192 bytes. The changes update both the Python and C++ layers to detect large binary parameters, use deferred execution (DAE) for streaming, and add new tests to verify correct handling of both small and large binary data.

Binary parameter streaming support:

• Updated _map_sql_type in cursor.py to detect large bytes/bytearray parameters (>8000 bytes) and mark them for VARBINARY(MAX) streaming, while still handling small binaries directly.
• Modified parameter binding in ddbc_bindings.cpp to use deferred execution for large binaries, and to allocate/bind buffers correctly for both small and large binary parameters.
• Enhanced SQLExecute_wrap in ddbc_bindings.cpp to stream large binary data using SQLPutData in chunks during execution.

Testing improvements:

• Refactored and expanded tests in test_004_cursor.py to separately verify small/medium binary inserts and to add a new test for inserting large binary data (>8000 bytes) using streaming. [1] [2]

[Copilot]

Pull Request Overview

This PR adds support for streaming large binary parameters (bytes and bytearray) to SQL Server using VARBINARY(MAX), removing the previous 8192-byte limitation. The implementation introduces deferred execution (DAE) for binary data larger than 8000 bytes while maintaining direct binding for smaller data.

Key changes:

• Updated parameter type mapping to detect large binary parameters and use VARBINARY(MAX) with streaming
• Modified C++ parameter binding to handle both small (direct) and large (streamed) binary data
• Enhanced SQL execution to stream large binary data in chunks using SQLPutData

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
mssql_python/cursor.py	Updated _map_sql_type to conditionally use VARBINARY(MAX) with DAE for binary data >8000 bytes
mssql_python/pybind/ddbc_bindings.cpp	Enhanced parameter binding and execution to support streaming large binary data
tests/test_004_cursor.py	Split binary data tests into separate small/large test cases

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[sumitmsft]

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