Cassandra 15135 trunk #1163
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Cassandra 15135 trunk #1163
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jbellis
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Jun 26, 2024
…apache#1163) * "all the keys between smallest and largest" is a terrible approximation of the keys in the search set that are actually present in the memtable; compute this actual subset (which is inexpensive to do) before either brute forcing or searching the index * brute force (reading vectors from the sstable and sorting by distance, instead of going through ann index) is observed to be 3x-5x more expensive per row than index scan. This incorporates that into the decision whether to use brute force, and makes the multiplier configurable; default is a more conservative 3x.
michaelsembwever
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Sep 25, 2024
…apache#1163) * "all the keys between smallest and largest" is a terrible approximation of the keys in the search set that are actually present in the memtable; compute this actual subset (which is inexpensive to do) before either brute forcing or searching the index * brute force (reading vectors from the sstable and sorting by distance, instead of going through ann index) is observed to be 3x-5x more expensive per row than index scan. This incorporates that into the decision whether to use brute force, and makes the multiplier configurable; default is a more conservative 3x.
michaelsembwever
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Jan 7, 2026
…apache#1163) * "all the keys between smallest and largest" is a terrible approximation of the keys in the search set that are actually present in the memtable; compute this actual subset (which is inexpensive to do) before either brute forcing or searching the index * brute force (reading vectors from the sstable and sorting by distance, instead of going through ann index) is observed to be 3x-5x more expensive per row than index scan. This incorporates that into the decision whether to use brute force, and makes the multiplier configurable; default is a more conservative 3x.
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