Terms aggs: only use ordinals on low-cardinality fields by default. #5304
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| for (AtomicReaderContext ctx : context.searchContext().searcher().getTopReaderContext().reader().leaves()) { | ||
| maxDoc = Math.max(maxDoc, ctx.reader().maxDoc()); | ||
| } | ||
| if (maxNumUniqueValues > (maxDoc >>> 4)) { |
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Maybe 'maxDoc >>> 4' should be configurable?
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Maybe as part of the hint itself like: map_less_128
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I'd rather not make it configurable given that users can still make the execution mode explicit via execution_hint. About the division by 16, this is a wild guess, my goal was to make sure that unique fields (eg. _id) would not use ordinals.
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+1 LGTM |
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LGTM |
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Ordinals tend to be slower and more wasteful memory-wise on high-cardinality fields.
Close #5303