Keep only none/zstd138 compression

[hnwyllmm]

Task Description

Keep only the none and zstd138 compression algorithms in the codebase.

Solution Description

This change removes support for other compression libraries (lz4, snappy, and older versions of zstd), retaining only the none (no compression) and zstd138 compression options.

Passed Regressions

Upgrade Compatibility

Other Information

Code Changes

┌──────────────┬───────────┐
│ Metric       │ Count     │
├──────────────┼───────────┤
│ Files Changed│ 866       │
├──────────────┼───────────┤
│ Lines Added  │ 12,115    │
├──────────────┼───────────┤
│ Lines Deleted│ 76,071    │
├──────────────┼───────────┤
│ Net Deletion │ 63,956    │
└──────────────┴───────────┘

Breakdown:

• Deleted source code for compression libraries (lz4/snappy/zstd directories): 53,548 lines
• Modified mysqltest/obtest files (name replacements): ~11,600 lines
• Modified C++ source files and unit tests: ~900 lines

Binary Size Impact

Using the zstd_1_3_8 compilation artifact as a reference (848KB .text segment / 2.4M .o file), the estimated impact of removing the three libraries:

┌─────────────┬──────────┬───────────────┐
│ Library     │ Source Lines │ Est. .text  │
├─────────────┼──────────┼───────────────┤
│ lz4         │ 6,765    │ ~200-300KB   │
├─────────────┼──────────┼───────────────┤
│ snappy      │ 2,987    │ ~150-200KB   │
├─────────────┼──────────┼───────────────┤
│ zstd (old)  │ 39,994   │ ~800-1000KB  │
├─────────────┼──────────┼───────────────┤
│ Total       │ 49,746   │ ~1.2-1.5MB   │
└─────────────┴──────────┴───────────────┘

The stripped binary is approximately 534MB. A reduction of ~1.2-1.5MB in the .text segment represents about 0.2-0.3% of the stripped binary size. The compression libraries themselves are not large; the primary benefits are in code simplicity and reduced maintenance cost.

Related Links

• DIMA-2026060200116500678

Release Note

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