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Ted Yu commented on HBASE-4344: ------------------------------- >From Amit: Earlier, before this patch, the essential ACID violation was occuring because some updates that are *newer* than the Scan's read point got included into the return because flush+read allowed them to be considered old. I don't see that problem anymore. The current violation for ACID semantics seems from the fact that some updates that *should* be included in the return (because the readPoint is further) are not being included. Looks like there is some compactions going on, during the run, and I need to investigate to see if somehow the updateReaders etc is not including a file that needs to be included. ------- So the patch is not ready for integration yet. > Persist memstoreTS to disk > -------------------------- > > Key: HBASE-4344 > URL: https://issues.apache.org/jira/browse/HBASE-4344 > Project: HBase > Issue Type: Sub-task > Reporter: Amitanand Aiyer > Assignee: Amitanand Aiyer > Fix For: 0.89.20100924 > > Attachments: 4344-v10.txt, 4344-v11.txt, 4344-v2.txt, 4344-v4.txt, > 4344-v5.txt, 4344-v6.txt, 4344-v7.txt, 4344-v8.txt, 4344-v9.txt, patch-2 > > > Atomicity can be achieved in two ways -- (i) by using a multiversion > concurrency system (MVCC), or (ii) by ensuring that "new" writes do not > complete, until the "old" reads complete. > Currently, Memstore uses something along the lines of MVCC (called RWCC for > read-write-consistency-control). But, this mechanism is not incorporated for > the key-values written to the disk, as they do not include the memstore TS. > Let us make the two approaches be similar, by persisting the memstoreTS along > with the key-value when it is written to the disk. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira