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98323be296
We want to exclude repair with tablet migrations to avoid races between repair reads and writes with replica movement. Repair is not prepared to handle topology transitions in the middle. One reason why it's not safe is that repair may successfully write to a leaving replica post streaming phase and consider all replicas to be repaired, but in fact they are not, the new replica would not be repaired. Other kinds of races could result in repair failures. If repair writes to a leaving replica which was already cleaned up, such writes will fail, causing repair to fail. Excluding works by keeping effective_replication_map_ptr in a version which doesn't have table's tablets in transitions. That prevents later transitions from starting because topology coordinator's barrier will wait for that erm before moving to a stage later than allow_write_both_read_old, so before any requets start using the new topology. Also, if transitions are already running, repair waits for them to finish. Fixes #17658. Fixes #18561.