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Zhihong Ted Yu commented on HBASE-6195: --------------------------------------- In patch v3: {code} + long now = EnvironmentEdgeManager.currentTimeMillis(); Integer lid = getLock(lockid, row, true); {code} Variable now isn't actually referenced. Do we need it ? {code} + //store the kvs to the tmp memory for write hlog first, then write memory {code} The above should read: 'to temporary memstore before writing HLog' > Increment data will lost when the memstore flushed > -------------------------------------------------- > > Key: HBASE-6195 > URL: https://issues.apache.org/jira/browse/HBASE-6195 > Project: HBase > Issue Type: Bug > Components: regionserver > Reporter: Xing Shi > Attachments: HBASE-6195-trunk-V2.patch, HBASE-6195-trunk-V3.patch, > HBASE-6195-trunk.patch > > > There are two problems in increment() now: > First: > I see that the timestamp(the variable now) in HRegion's Increment() is > generated before got the rowLock, so when there are multi-thread increment > the same row, although it generate earlier, it may got the lock later. > Because increment just store one version, so till now, the result will still > be right. > When the region is flushing, these increment will read the kv from snapshot > and memstore with whose timestamp is larger, and write it back to memstore. > If the snapshot's timestamp larger than the memstore, the increment will got > the old data and then do the increment, it's wrong. > Secondly: > Also there is a risk in increment. Because it writes the memstore first and > then HLog, so if it writes HLog failed, the client will also read the > incremented value. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira