[poc] persist: explicit schema registration #33920
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This commit changes `PersistClient::open_writer` to not perform schema registration anymore. This enables the creation of `WriteHandle`s with schemas that haven't been made durable, a feature necessary to ensure we can perform schema migrations in 0dt read-only mode without the risk of poisoning durable state. Writing to a shard with an incompatible schema is unsound, so CaA calls now assert that a schema has been registered. Persist users that plan to perform writes must ensure that they register the write schema _before_ creating the write handle. Usually they should do that when they create new shards.
teskje
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This commit changes
PersistClient::open_writerto not perform schema registration anymore. This enables the creation ofWriteHandles with schemas that haven't been made durable, a feature necessary to ensure we can perform schema migrations in 0dt read-only mode without the risk of poisoning durable state.Writing to a shard with an incompatible schema is unsound, so CaA calls now assert that a schema has been registered. Persist users that plan to perform writes must ensure that they register the write schema before creating the write handle. Usually they should do that when they create new shards.
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$T ⇔ Proto$Tmapping (possibly in a backwards-incompatible way), then it is tagged with aT-protolabel.