adapter: keep catalog upper up-to-date with read ts#35402
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teskje wants to merge 1 commit intoMaterializeInc:mainfrom
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adapter: keep catalog upper up-to-date with read ts#35402teskje wants to merge 1 commit intoMaterializeInc:mainfrom
teskje wants to merge 1 commit intoMaterializeInc:mainfrom
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This commit introduces a way to advance the frontier of the catalog shard without appending any new updates and then uses that to keep the catalog shard's frontier up to date with the oracle read ts. This ensures that `mz_catalog_raw` is always readable with strict serializable isolation, since under that isolation level, the oracle read ts will be used as the query timestamp. This increases the amount of CRDB queries we make, instead of bumping only the txn-wal, we now additionally need to bump the catalog shard. But note that in two of the three instances the `advance_upper` call replaces a `confirm_leadership` call, which also did a CRDB query, so one can hope that the resulting number of CRDB calls is similar. This could potentially be further improved by moving the catalog shard into txn-wal, but that's a larger lift so we leave it as future work.
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This PR introduces a way to advance the frontier of the catalog shard without appending any new updates and then uses that to keep the catalog shard's frontier up to date with the oracle read ts. This ensures that
mz_catalog_rawis always readable with strict serializable isolation, since under that isolation level, the oracle read ts will be used as the query timestamp.This increases the amount of CRDB queries we make, instead of bumping only the txn-wal, we now additionally need to bump the catalog shard. But note that in two of the three instances the
advance_uppercall replaces aconfirm_leadershipcall, which also did a CRDB query, so one can hope that the resulting number of CRDB calls is similar.This could potentially be further improved by moving the catalog shard into txn-wal, but that's a larger lift so we leave it as future work.
Motivation
Closes SQL-117