Samarth Jain created PHOENIX-3326:
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Summary: Restoring SYSTEM.CATALOG from snapshot causes clients to
run into UpgradeInProgressException
Key: PHOENIX-3326
URL: https://issues.apache.org/jira/browse/PHOENIX-3326
Project: Phoenix
Issue Type: Bug
Reporter: Samarth Jain
Assignee: Samarth Jain
We create a snapshot of the SYSTEM.CATALOG table only after the client is able
to successfully acquire a distributed mutex of sorts. This means the snapshot
also ends up containing the row that serves as the mutex. Now when restoring
the table from snapshot, this rows is still present which causes clients to
throw UpgradeInProgress exception.
I can think of a couple of ways to fix this:
1) Do the checkAndPut for the UPGRADE_MUTEX after creating the snapshot. I am
not too sure though how about HBase handles concurrent snapshot requests. Do
clients get an exception? Also we potentially could end up creating more
snapshots than we really need to.
2) Do the checkAndPut for the UPGRADE_MUTEX in a different table (possibly
SYSTEM.SEQUENCE). This way the restored snapshot won't have the row. We would
need to delete the row from SYSTEM.SEQUENCE after the upgrade is done
(successfully or unsuccessfully).
[~jamestaylor] - WDYT?
FYI, [~lhofhansl] - this is probably a blocker for 4.8.1
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