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[ntuple] Merger: avoid resealing if not needed #20112
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Currently we either "fast merge" the page (i.e. we copy it as-is to the
destination) or we reseal it if fast merging is not possible.
There is a middle ground where we can avoid resealing if only the page
compression differs but not the on-disk encoding.
We were not currently leveraging this and doing the extra work of
resealing the pages in all cases where just recompression could be done.
With this PR we introduce this middle ground case ("L2 merging", aka
"recompress merging") which skips the resealing (thus the re-encoding)
of the pages whenever possible.
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Test Results
22 files 22 suites 3d 19h 52m 59s ⏱️
3 692 tests 3 691 ✅ 0 💤 1 ❌
79 273 runs 79 272 ✅ 0 💤 1 ❌
For more details on these failures, see this check.
Results for commit bfdeb3e.
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Currently we either "fast merge" the page (i.e. we copy it as-is to the destination) or we reseal it if fast merging is not possible (which happens where the compression or the on-disk encoding don't match).
There is a middle ground where we can avoid resealing if only the page compression differs but not the on-disk encoding.
We were not currently leveraging this and doing the extra work of resealing the pages in all cases where just recompression could be done.
With this PR we introduce this middle ground case ("L2 merging", aka "recompress merging") which skips the resealing (thus the re-encoding) of the pages whenever possible.
(see here for the L2 terminology)
Checklist: