Enis Soztutar created HBASE-9906:
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Summary: Restore snapshot fails to restore the meta edits
sporadically
Key: HBASE-9906
URL: https://issues.apache.org/jira/browse/HBASE-9906
Project: HBase
Issue Type: New Feature
Components: snapshots
Reporter: Enis Soztutar
Assignee: Enis Soztutar
Fix For: 0.98.0, 0.96.1, 0.94.14
After snaphot restore, we see failures to find the table in meta:
{code}
> disable 'tablefour'
> restore_snapshot 'snapshot_tablefour'
> enable 'tablefour'
ERROR: Table tablefour does not exist.'
{code}
This is quite subtle. From the looks of it, we successfully restore the
snapshot, do the meta updates, return to the client about the status. The
client then tries to do an operation for the table (like enable table, or scan
in the test outputs) which fails because the meta entry for the region seems to
be gone (in case of single region, the table will be reported missing).
Subsequent attempts for creating the table will also fail because the table
directories will be there, but not the meta entries.
For restoring meta entries, we are doing a delete then a put to the same region:
{code}
2013-11-04 10:39:51,582 INFO
org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper: region to restore:
76d0e2b7ec3291afcaa82e18a56ccc30
2013-11-04 10:39:51,582 INFO
org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper: region to remove:
fa41edf43fe3ee131db4a34b848ff432
...
2013-11-04 10:39:52,102 INFO org.apache.hadoop.hbase.catalog.MetaEditor:
Deleted [{ENCODED => fa41edf43fe3ee131db4a34b848ff432, NAME =>
'tablethree_mod,,1383559723345.fa41edf43fe3ee131db4a34b848ff432.', STARTKEY =>
'', ENDKEY => ''}, {ENCODED => 76d0e2b7ec3291afcaa82e18a56ccc30, NAME =>
'tablethree_mod,,1383561123097.76d0e2b7ec3291afcaa82e18a56ccc30.', STARTKE
2013-11-04 10:39:52,111 INFO org.apache.hadoop.hbase.catalog.MetaEditor: Added 1
{code}
The root cause for this sporadic failure is that, the delete and subsequent put
will have the same timestamp if they execute in the same ms. The delete will
override the put in the same ts, even though the put have a larger ts.
See: HBASE-9905, HBASE-8770
Credit goes to [~huned] for reporting this bug.
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