db: remove compactionIter's sameStripeNonSkippable#3221
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jbowens wants to merge 2 commits intocockroachdb:masterfrom
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db: remove compactionIter's sameStripeNonSkippable#3221jbowens wants to merge 2 commits intocockroachdb:masterfrom
jbowens wants to merge 2 commits intocockroachdb:masterfrom
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Remove the keyspan.InternalIteratorShim that was intended to be a temporary bridge to allow range deletions to be surfaced within the compaction iterator, replacing it with the keyspan.InterleavingIter. This mirrors the mechanics of range keys. Follow up work will be able to simplify the compaction iterator logic now that range deletions are always interleaved at the maximal sequence number. Informs cockroachdb#3082.
This commit removes the compaction iterator's concept of a key that lies within the same snapshot stripe but is non-skippable. These "non-skippable" keys lead to bizarre behavior, such as a sequence like: a.MERGE.5 a.RANGEDEL.4 a.MERGE.4 yielding the separate unmerged a.MERGE.5 and a.MERGE.4 internal keys (Note a.RANGEDEL.4 does not delete a.MERGE.4 because they share the same sequence number.) The sameStripeNonSkippable fell out of the fact that range deletions were previously interleaved by the input iterator at their start key with their sequence number. These sameStripeNonSkippable could interrupt any logic iterating across the keys of a stripe, complicating the compaction iterator logic. With cockroachdb#3219, range deletions began to be interleaved at their start key with the maximal sequence number, ensuring they never interrupt the keys of a snapshot stripe. In some instances INVALID keys were also returned with sameStripeNonSkippable. These keys are now treated similarly to other errors encountered during iteration: i.err is set and newStripeNewKey is returned. Close cockroachdb#3082.
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Merged into #3219 to produce a more coherent diff. |
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The first commit is from #3219 and should be reviewed there.
This commit removes the compaction iterator's concept of a key that lies within
the same snapshot stripe but is non-skippable. These "non-skippable" keys lead
to bizarre behavior, such as a sequence like:
a.MERGE.5 a.RANGEDEL.4 a.MERGE.4
yielding the separate unmerged a.MERGE.5 and a.MERGE.4 internal keys (Note
a.RANGEDEL.4 does not delete a.MERGE.4 because they share the same sequence
number.)
The sameStripeNonSkippable fell out of the fact that range deletions were
previously interleaved by the input iterator at their start key with their
sequence number. These sameStripeNonSkippable could interrupt any logic
iterating across the keys of a stripe, complicating the compaction iterator
logic. With #3219, range deletions began to be interleaved at their start key
with the maximal sequence number, ensuring they never interrupt the keys of a
snapshot stripe.
In some instances INVALID keys were also returned with sameStripeNonSkippable.
These keys are now treated similarly to other errors encountered during
iteration: i.err is set and newStripeNewKey is returned.
Close #3082.