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Great! it can help to bypass the performance issue caused by scalar subqueries mentioned in 7329 and 7077 . In this case, given queries introducing huge aggregateStateData in scalar subqueries, one could store the aggregateStateData in a temporary table, and use joinGet to retrieve, such that scalar subqueries are not triggered without cumbersome string escaping and copying. |
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An Join table behaves append-only. Any row is not update-able. So joinGet always returns const value. FYI, following sql still oom. |
It's updatable but not via the alter interface. #3973
That's because bitmap types are value owners not value handlers like StringRef, and you are generating non-constant blocks with same bitmaps. You can try combining it with LowCardinality. It might work. |
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The problem is discovered by @yingfeng and his collegue when testing joinGet with bitmaps.
Consider the following query,
without constness-aware, joinGet will duplicate bitmaps.
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