opt: prune unnecessary check columns #56007
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This commit updates the optimizer to prune synthesized `CHECK` constraint columns for `UPDATES` when columns referenced in the constraints are not updated. This may also allow the optimizer to no longer fetch those referenced columns. This should provide a performance benefit for `UDPATE`s to tables with check constraints. Notably, tables that have been given many column families (in order to reduce contention) should see a significant reduction in contention for `UPDATE`s that mutate a subset of column families. Informs cockroachdb#51526 Release note (performance improvement): Previously, all `CHECK` constraints defined on a table would be tested for every `UPDATE` to the table. Now, a check constraint will not be tested for validity when the values of columns it references are not being updated. The referenced columns are no longer fetchecd in cases where they were only fetched to test `CHECK` constraints.
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RaduBerinde
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Oct 27, 2020
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complete! 1 of 0 LGTMs obtained (waiting on @RaduBerinde and @rytaft)
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This commit updates the optimizer to prune synthesized
CHECKconstraint columns for
UPDATESwhen columns referenced in theconstraints are not updated. This may also allow the optimizer to no
longer fetch those referenced columns.
This should provide a performance benefit for
UDPATEs to tables withcheck constraints. Notably, tables that have been given many column
families (in order to reduce contention) should see a significant
reduction in contention for
UPDATEs that mutate a subset of columnfamilies.
Informs #51526
Release note (performance improvement): Previously, all
CHECKconstraints defined on a table would be tested for every
UPDATEto thetable. Now, a check constraint will not be tested for validity when the
values of columns it references are not being updated. The referenced
columns are no longer fetchecd in cases where they were only fetched to
test
CHECKconstraints.