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https://issues.apache.org/jira/browse/HBASE-14004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15049947#comment-15049947
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Heng Chen commented on HBASE-14004:
-----------------------------------
{quote}
1, 2, 3, 4, 5---this is normal order
1, 3, 2, 4, 5---the order is wrong but each log we only read once.
1, 1, 2, 3, 4, 5---we replay one entry twice but they are continuous
1, 2, 3, 1, 4, 5----we replay one entry twice and they are not continuous
1, 2, 3, 1, 2, 3, 4, 5---the order is wrong but the subsequence is repeat so we
make sure the order
{quote}
[~yangzhe1991] only the first one is right now in current logic.
WAL is RS Level, but replay is in Region Level, so in wal , seqId in
increased one by one, but we can't ensure it in region Level when replay,
that's why i mentioned i made a mistake in HBASE-14949. I will dig it deeper.
Would you mind update the doc as we mentioned above, Zhe?
> [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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