opt: explore splitting disjunction over same column #157083
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michae2
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Nov 17, 2025
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complete! 0 of 0 LGTMs obtained (waiting on @DrewKimball and @mgartner)
mgartner
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Nov 17, 2025
| └── c:3 | ||
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| opt expect=SplitDisjunction | ||
| SELECT c, a FROM t157073 WHERE c = 5 AND (b < 9990 OR b >= 9990) |
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So in this case, we split the disjunction but those two branches could not be index-accelerated, so we pick a full scan instead. Is that correct? Might be good to leave a short note explaining that.
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Yes, that's correct. I added a note (and a few more test cases I thought of).
The SplitDisjunction rules did not consider disjunctions over expressions referencing the same column interesting, because normally these disjunctions can become multiple spans in the same constrained scan. There is one special case, however, where disjunctions over the same column might be interesting: if the table has multiple partial indexes with different predicates referencing that column. In that case we might be able to use a different partial index for each side of the disjunction. Fixes: cockroachdb#157073 Release note (performance improvement): This commit teaches the optimizer to split disjunctions on the same column into unions when there are multiple partial indexes with different predicates referencing that column.
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TFTR! bors r=mgartner |
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The SplitDisjunction rules did not consider disjunctions over expressions referencing the same column interesting, because normally these disjunctions can become multiple spans in the same constrained scan. There is one special case, however, where disjunctions over the same column might be interesting: if the table has multiple partial indexes with different predicates referencing that column. In that case we might be able to use a different partial index for each side of the disjunction.
Fixes: #157073
Release note (performance improvement): This commit teaches the optimizer to split disjunctions on the same column into unions when there are multiple partial indexes with different predicates referencing that column.