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1552044615
Tablet migration may execute a global token metadata barrier before executing updates of system.tablets. If table is dropped while the barrier is happening, the updates will bring back rows for migrated tablets in a table which is no longer there. This will cause tablet metadata loading to fail with error: missing_column (missing column: tablet_count) Like in this log line: storage_service - raft topology: topology change coordinator fiber got error raft::stopped_error (Raft instance is stopped, reason: "background error, std::_Nested_exception<raft::state_machine_error> (State machine error at raft/server.cc:1206): std::_Nested_exception<std::runtime_error> (Failed to read tablet metadata): missing_column (missing column: tablet_count)œ") The fix is to read and execute the updates in a single group0 guard scope, and move execution of the barrier later. We cannot now generate updates in the same handle_tablet_migration() step if barrier needs to be executed, so we resuse the mechanism for two-step stage transition which we already have for handling of streaming. The next pass will notice that the barrier is not needed for a given tablet and will generate the stage update. Fixes #15061 Closes #15069