clusterversion,storage: add explicit version for split user keys #84887
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Pebble ceased splitting user keys across multiple sstables in a single level in cockroachdb/pebble@a860bbad. A Pebble format major version was added in 22.1 to mark existing tables with split user that formed an "atomic compaction unit" for compaction. The compaction to recombine the split keys happens at a low priority within Pebble, so there is no guarantee that these tables have been recombined. Pebble range key support depends on having split user keys recombined. As such, the Pebble migration to upgrade to a version that support range keys must first perform a blocking migration to compact tables with split user keys. Currently, the Cockroach cluster version `EnsurePebbleFormatVersionRangeKeys` ratchets the Pebble version through both the split user keys migration, up to the version that supports range keys. Strictly speaking, the Pebble format version migration will take care of the sequencing. However, to provide better visibility into the various Pebble migrations, and to cater for the fact that the split user keys migration may take some time to recombine the necessary tables, a dedicated cluster version for the split keys migration is added. This dedicated cluster version makes it unambiguous what's blocking the Cockroach version finalization. Release note (backward-incompatible change, ops change): A cluster version is added to allow Pebble to recombine certain SSTables (specifically, user keys that are split across multiple files in a level of the LSM). Recombining the split user keys is required for supporting the range keys feature. The migration to recombine the SSTables is expected to be short (split user keys are rare in practice), but will block subsequent migrations until all tables have been recombined. The `storage.marked-for-compaction-files` time series metric can show the progress of the migration. Close cockroachdb#84012.
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This change is |
nicktrav
commented
Jul 21, 2022
| Version: roachpb.Version{Major: 22, Minor: 1, Internal: 6}, | ||
| }, | ||
| { | ||
| Key: EnablePebbleFormatVersionRangeKeys, | ||
| Key: EnsurePebbleFormatVersionRangeKeys, |
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I shifted everything down to slot in the PebbleFormatSplitUserKeysMarkedCompacted version before the range keys version. I think that's fine?
jbowens
approved these changes
Jul 22, 2022
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Reviewed 2 of 5 files at r1, all commit messages.
Reviewable status:complete! 1 of 0 LGTMs obtained (waiting on @itsbilal and @nicktrav)
pkg/clusterversion/cockroach_versions.go line 528 at r1 (raw file):
Previously, nicktrav (Nick Travers) wrote…
I shifted everything down to slot in the
PebbleFormatSplitUserKeysMarkedCompactedversion before the range keys version. I think that's fine?
I think it should be fine too
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Flake is in the logictest. Ignoring. TFTR! bors r=jbowens |
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Build succeeded: |
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Pebble ceased splitting user keys across multiple sstables in a single
level in cockroachdb/pebble@a860bbad. A Pebble format major version was
added in 22.1 to mark existing tables with split user that formed an
"atomic compaction unit" for compaction. The compaction to recombine the
split keys happens at a low priority within Pebble, so there is no
guarantee that these tables have been recombined.
Pebble range key support depends on having split user keys recombined.
As such, the Pebble migration to upgrade to a version that support range
keys must first perform a blocking migration to compact tables with
split user keys.
Currently, the Cockroach cluster version
EnsurePebbleFormatVersionRangeKeysratchets the Pebble version throughboth the split user keys migration, up to the version that supports
range keys. Strictly speaking, the Pebble format version migration will
take care of the sequencing.
However, to provide better visibility into the various Pebble
migrations, and to cater for the fact that the split user keys migration
may take some time to recombine the necessary tables, a dedicated
cluster version for the split keys migration is added. This dedicated
cluster version makes it unambiguous what's blocking the Cockroach
version finalization.
Release note (backward-incompatible change, ops change): A cluster
version is added to allow Pebble to recombine certain SSTables
(specifically, user keys that are split across multiple files in a level
of the LSM). Recombining the split user keys is required for supporting
the range keys feature. The migration to recombine the SSTables is
expected to be short (split user keys are rare in practice), but will
block subsequent migrations until all tables have been recombined. The
storage.marked-for-compaction-filestime series metric can show theprogress of the migration.
Close #84012.