opt: fix infinite cost estimate for lookup join with limit hint #46440
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Due to a divide-by-zero error, the coster estimated an infinite limit hint -- and therefore an infinite cost -- for lookup joins that had a limit hint and zero output rows. This caused an internal error during planning. This commit fixes the problem by fixing the divide-by-zero error. Instead of an infinite limit hint, it estimates a limit hint of 0. Fixes cockroachdb#46187 Release justification: This is a low risk, high benefit change to existing functionality. Release note (bug fix): Fixed an internal error that could occur during planning for some queries with a join and negative LIMIT.
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RaduBerinde
approved these changes
Mar 23, 2020
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Reviewable status:
complete! 1 of 0 LGTMs obtained (waiting on @RaduBerinde)
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bors r+ |
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Due to a divide-by-zero error, the coster estimated an infinite limit hint --
and therefore an infinite cost -- for lookup joins that had a limit hint and
zero output rows. This caused an internal error during planning.
This commit fixes the problem by fixing the divide-by-zero error. Instead of
an infinite limit hint, it estimates a limit hint of 0.
Fixes #46187
Release justification: This is a low risk, high benefit change to existing
functionality.
Release note (bug fix): Fixed an internal error that could occur during
planning for some queries with a join and negative LIMIT.