Schema migration to ensure sentinel rows exist #1911
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Note that I've moved sentinel row encoding and decoding on |
wilhuff
approved these changes
Oct 5, 2018
| */ | ||
| const LevelDbMigrations::SchemaVersion kSchemaVersion = 3; | ||
| const LevelDbMigrations::SchemaVersion kSchemaVersion = 4; |
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Is it worth attempting to keep the migration numbers in sync with the other clients?
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We would have to implement held-write-acks removal before this, which I don't think is a worthwhile delay.
| * Given an encoded sentinel row, return the sequence number. | ||
| */ | ||
| static model::ListenSequenceNumber DecodeSentinel( | ||
| const absl::string_view& slice); |
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absl::string_view is intended to be passed by value (it's just a pointer and a size, which is cheaper to just copy rather than take a reference).
added 2 commits
October 5, 2018 15:35
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Ensures that we have a sequence number written down for each document in the remote document cache. We already have the code to sequence numbers for new documents (via target updates, mutations, and limbo resolutions). However, we have never gone back to make sure existing documents have sequence numbers.
This migration will stamp the highest sequence number observed onto each remote document which does not yet have a sentinel row.