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https://issues.apache.org/jira/browse/HBASE-9469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13915428#comment-13915428
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Feng Honghua commented on HBASE-9469:
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Thanks [~terry_zhang] for comment!
bq.we need to make sure client write both side is a transaction if you want to
data is consistent.
I've explained in above comment that neither writing both sides from client nor
letting master cluster synchronously push WALEdits to peer can improve the
overall availability, both ways improve the read availability at the cost of
write availability : now the write fails in face of either cluster outage...
IMHO, to improve better read availability *without* hurting write availability,
we need similar treatment as Megastore or Spanner.
> Synchronous replication
> -----------------------
>
> Key: HBASE-9469
> URL: https://issues.apache.org/jira/browse/HBASE-9469
> Project: HBase
> Issue Type: New Feature
> Reporter: Feng Honghua
>
> Scenario:
> A/B clusters with master-master replication, client writes to A cluster and A
> pushes all writes to B cluster, and when A cluster is down, client switches
> writing to B cluster.
> But the client's write switch is unsafe due to the replication between A/B is
> asynchronous: a delete to B cluster which aims to delete a put written
> earlier can fail due to that put is written to A cluster and isn't
> successfully pushed to B before A is down. It can be worse if this delete is
> collected(flush and then major compact occurs) before A cluster is up and
> that put is eventually pushed to B, the put won't ever be deleted.
> Can we provide per-table/per-peer synchronous replication which ships the
> according hlog entry of write before responsing write success to client? By
> this we can guarantee the client that all write requests for which he got
> success response when he wrote to A cluster must already have been in B
> cluster as well.
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