Address ignored source read performance issue.#145077
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martijnvg merged 1 commit intoelastic:mainfrom Mar 27, 2026
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With the new DOC_VALUES_IGNORED_SOURCE ignored source format, the binary doc values instance (fetched via MultiValuedSortedBinaryDocValues) gets re-initialized for each docid that needs to read ignored source. The binary doc values instance keeps the current uncompressed block around, so that subsequent docids can read without having to decompress if the docid needs current block. Because binary doc values instance each re-initialized each time, this doesn't happen any more each each docid always needs to compress a block.
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Mar 30, 2026
With the new DOC_VALUES_IGNORED_SOURCE ignored source format, the binary doc values instance (fetched via MultiValuedSortedBinaryDocValues) gets re-initialized for each docid that needs to read ignored source. The binary doc values instance keeps the current uncompressed block around, so that subsequent docids can read without having to decompress if the docid needs current block. Because binary doc values instance gets re-initialized each time ignored source gets read for a docid, the binary doc values implementation doesn't get a chance to reuse current decompressed block. With the result that each docid always decompresses a compressed block.
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With the new DOC_VALUES_IGNORED_SOURCE ignored source format, the binary doc values instance (fetched via MultiValuedSortedBinaryDocValues) gets re-initialized for each docid that needs to read ignored source.
The binary doc values instance keeps the current uncompressed block around, so that subsequent docids can read without having to decompress if the docid needs current block. Because binary doc values instance gets re-initialized each time ignored source gets read for a docid, the binary doc values implementation doesn't get a chance to reuse current decompressed block. With the result that each docid always decompresses a compressed block.
Marking as non-issue, since this bug hasn't been released in a stateful release yet.
See attached flamegraph for how this issue manifests:
rally.html