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jeremyhi
4ef312ecf2
* docs: add the object store WAL RFC Propose an object store backed write-ahead log as a WAL provider next to Raft Engine and Kafka: a datanode batches the entries of its regions into immutable objects under one prefix, creates each object conditionally under a monotonically increasing sequence, acknowledges a write once its object is durable by default, and replays each region from its own segments after listing the prefix. A reference implementation exists and follows this RFC in a series of pull requests; the document describes it and marks what is proposed on top of it. Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: link the object store WAL RFC to its tracking issue Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: describe the predecessor chain and instance epoch of the object store WAL Recovery replays only the chain of objects that ends at the latest complete object, and every open starts a new epoch with an empty start object, so an object whose create was reported as failed is never replayed once a later append has been acknowledged. Update the object format, recovery, writing, the failure matrix, the garbage collection constraints, compatibility, evidence, drawbacks and the cluster mode alignment accordingly. Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: identify object store WAL objects by sequence and epoch Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: derive the object store WAL epoch from the start object sequence Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: separate the retryable and the conflicting start object outcomes Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: describe garbage collection of the object store WAL through the reclaim boundary Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: judge vanished objects after chain selection and fix the evidence references Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: record the stop-time conflict and the completed fault matrix in the object store WAL RFC Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: limit the stop-time conflict to objects of the same or a later epoch Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: keep the conflicting-content condition in the stop-time conflict sentence Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: report the S3 write path measurements of the object store WAL Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: qualify the seal timer findings and link the S3 runs Signed-off-by: jeremyhi <fengjiachun@gmail.com> * docs: state the serial durable cycle behind the one-batch-per-interval observation Signed-off-by: jeremyhi <fengjiachun@gmail.com> --------- Signed-off-by: jeremyhi <fengjiachun@gmail.com>