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https://issues.apache.org/jira/browse/HBASE-14004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15044576#comment-15044576
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Phil Yang commented on HBASE-14004:
-----------------------------------
{quote}
Some entries in new WAL may have smaller seqid than entries in old WAL as our
logical, right?
{quote}
Yes, that is why we should make sure WAL reader can filter entries that it has
seen before. Two entries with same id may not adjacent, maybe two WAL files are
just like this:
[1, 2, 3, 4, 5, 6]
[4, 5, 6, 7]
If when writing first WAL we only make sure we have hflushed entries no larger
than 3
> [Replication] Inconsistency between Memstore and WAL may result in data in
> remote cluster that is not in the origin
> -------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-14004
> URL: https://issues.apache.org/jira/browse/HBASE-14004
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Reporter: He Liangliang
> Priority: Critical
> Labels: replication, wal
>
> Looks like the current write path can cause inconsistency between
> memstore/hfile and WAL which cause the slave cluster has more data than the
> master cluster.
> The simplified write path looks like:
> 1. insert record into Memstore
> 2. write record to WAL
> 3. sync WAL
> 4. rollback Memstore if 3 fails
> It's possible that the HDFS sync RPC call fails, but the data is already
> (may partially) transported to the DNs which finally get persisted. As a
> result, the handler will rollback the Memstore and the later flushed HFile
> will also skip this record.
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