feat(sql): require a query hint to enable rare-symbols optimization in ASOF JOIN#6333
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bluestreak01 merged 3 commits intomasterfrom Oct 31, 2025
Merged
feat(sql): require a query hint to enable rare-symbols optimization in ASOF JOIN#6333bluestreak01 merged 3 commits intomasterfrom
bluestreak01 merged 3 commits intomasterfrom
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The Memoized Scan algorithm for ASOF JOIN on symbol column has two kinds of caching:
For Match Caching, we only need a single hash lookup per LHS row for a cache hit, and another one for a cache miss.
For Drive-By Caching, we need a hash lookup for every visited RHS row. It pays off when many of the symbols to look for occur in the deep past of the RHS table. It allows us to make just one deep scan and find all of them. However, when there aren't many such symbols, hash lookups introduce a significant overhead, and result in worse performance in many typical cases.
Therefore, we're putting Drive-By Caching behind a query hint.