Details
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New Feature
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Status: Resolved
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Major
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Resolution: Fixed
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Description
A scan corresponding to a tablet failure causes the entire SQL to fail on the common query engines, such as Impala. Though we have the fault-tolerant feature by "SetFaultTolerant()", Impala doesn't use it right now since that will make lower throughput. Thus, lots of SQL that are running will fail when we shutdown/reboot/upgrade the tserver. That can be scary.
Maybe we can do some improvement in this area, for example, the tablets are not allowed to be scanned after the tserver is in maintenance mode (KUDU-2069). And for the LEADER_ONLY mode scanning, the leader role needs to be shifted from the maintenance tserver. Then we can shutdown the tserver smoothly after all the existing SQL are completed.