release-20.1: coldata: fix updating offsets of bytes in Batch.SetLength #59257
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In `SetLength` method we are maintaining the invariant of `Bytes` vectors that the offsets are non-decreasing sequences. Previously, this was done incorrectly when a selection vector is present on the batch which could lead to out of bounds errors (caught by our panic-catcher) some time later. This is now fixed by correctly paying attention to the selection vector. I neither can easily come up with an example query that would trigger this condition nor can I prove that it won't occur, but I think we have seen a single sentry report that could be explained by this bug, so I think it's worth backporting. Release note (bug fix): Previously, CockroachDB could encounter an internal error when executing queries with BYTES or STRING types via the vectorized engine in rare circumstances, and now this is fixed.
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asubiotto
approved these changes
Jan 25, 2021
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Reviewed 1 of 1 files at r1.
Reviewable status:complete! 1 of 0 LGTMs obtained (waiting on @yuzefovich)
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Backport 1/2 commits from #59028.
/cc @cockroachdb/release
In
SetLengthmethod we are maintaining the invariant ofBytesvectors that the offsets are non-decreasing sequences. Previously, this
was done incorrectly when a selection vector is present on the batch
which could lead to out of bounds errors (caught by our panic-catcher)
some time later. This is now fixed by correctly paying attention to the
selection vector.
I neither can easily come up with an example query that would trigger
this condition nor can I prove that it won't occur, but I think we have
seen a single sentry report that could be explained by this bug, so I
think it's worth backporting.
Fixes: #57297.
Release note (bug fix): Previously, CockroachDB could encounter an
internal error when executing queries with BYTES or STRING types via the
vectorized engine in rare circumstances, and now this is fixed.