kv: stop encoding or decoding synthetic timestamp bit in/from mvcc keys #105523
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Informs cockroachdb#101938. This commit removes logic in mvcc key encoding routines that handle synthetic timestamps. As a result, we no longer write keys with synthetic timestamps, though we retain the ability to decode them. As described in cockroachdb#72121 (comment) and later in cockroachdb@24c56df (see "Future improvements"), the introduction of the mvcc value header and the optional, per-version local timestamp paved the way for the removal of synthetic timestamps. MVCC keys no longer need to carry the synthetic bit in order for reads from GLOBAL tables to behave properly. As a result, we no longer need to write it. Release note: None
Informs cockroachdb#101938. This commit removes logic in mvcc key decoding routines to decode synthetic timestamps. We retain the ability to decode keys with the synthetic timestamp bit set, but we simply ignore its presence. As discussed in the previous commit, the role of these synthetic timestamp markers was eliminated in cockroachdb#80706 by the local_timestamp field in the mvcc value header, which was first present in v22.2. v23.2 does not require compatibility with v22.2, so it can rely on the fact that any txn that has a synthetic timestamp (because it writes in the future) will also write local timestamps into each of its values. Release note: None
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sumeerbhola
approved these changes
Jul 10, 2023
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Reviewed 6 of 6 files at r1, 7 of 7 files at r2, all commit messages.
Reviewable status:complete! 1 of 0 LGTMs obtained (waiting on @nvanbenschoten)
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TFTR! bors r=sumeerbhola |
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This was referenced Jan 3, 2024
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Informs #101938.
This first commit removes logic in mvcc key encoding routines that handle synthetic timestamps. As a result, we no longer write keys with synthetic timestamps, though we retain the ability to decode them.
The second commit removes logic in mvcc key decoding routines to decode synthetic timestamps. We retain the ability to decode keys with the synthetic timestamp bit set, but we simply ignore its presence.
As described in #72121 (comment) and later in 24c56df (see "Future improvements"), the introduction of the mvcc value header and the optional, per-version local timestamp paved the way for the removal of synthetic timestamps. MVCC keys no longer need to carry the synthetic bit in order for reads from GLOBAL tables to behave properly. As a result, we no longer need to write it.
Release note: None