LUCENE-9827: avoid wasteful recompression for small segments #28
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Require that the segment has enough dirty documents to create a clean chunk before recompressing during merge, there must be at least maxChunkSize. This prevents wasteful recompression with small flushes (e.g. every document): we ensure recompression achieves some "permanent" progress. Expose maxDocsPerChunk as a parameter for Term vectors too, matching the stored fields format. This allows for easy testing.
If segment N needs recompression, we have to flush any buffered docs before bulk-copying segment N+1. Don't just increment numDirtyChunks, also make sure numDirtyDocs is incremented, too. This doesn't have a performance impact, and is unrelated to tooDirty() improvements, but it is easier to reason about things with correct statistics in the index.
janhoy
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May 12, 2021
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Require that the segment has enough dirty documents to create a clean
chunk before recompressing during merge, there must be at least maxChunkSize.
This prevents wasteful recompression with small flushes (e.g. every
document): we ensure recompression achieves some "permanent" progress.
Expose maxDocsPerChunk as a parameter for Term vectors too, matching the
stored fields format. This allows for easy testing.
See JIRA for more details: https://issues.apache.org/jira/browse/LUCENE-9827?focusedCommentId=17305712&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17305712