When performing a three-way merge, Use a patchBuffer to build the new primary index instead of a MutableMap. #9229
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… primary index instead of a MutableMap.
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@nicktobey DOLT
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@coffeegoddd DOLT
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reltuk
reviewed
May 20, 2025
| var conflicts *conflictMerger | ||
| eg.Go(func() error { | ||
| var err error | ||
| sec, conflicts, err = computeProllyTreePatches(ctx, tm, finalSch, mergeTbl, valueMerger, mergeInfo, diffInfo, patchBuffer, s) |
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@nicktobey DOLT
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MutableMaps are designed for caching point modifications to a table. But during merge, the new primary index is computed sequentially. There's no benefit to using a MutableMap here.
MutableMaps are built on top of the
ApplyMutationsfunction, which takes a sequential stream of modifications (called a PatchBuffer) and applies them to a chunker. This has the added benefit of being parallelizable: the patches are produced in one goroutine and consumed in another.Instead of using the MutableMap, we can extract the underlying PatchBuffer and use it directly. This should be both more performant, and more correct as it avoids a failure case with schema merges where the MutableMap flushes changes to disk and writes a chunk containing rows with different schemas.