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From "Murtadha Hubail (Code Review)" <>
Subject Change in hyracks[master]: Introducing data replication API to LSM indexes
Date Mon, 21 Sep 2015 05:26:20 GMT
Murtadha Hubail has posted comments on this change.

Change subject: Introducing data replication API to LSM indexes

Patch Set 4:

File hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/replication/

Line 23:         METADATA
> Why metadata should be a special case?
METADATA job means that it is some metadata file(s) (.metadata). Unlike LSM_COMPONENT jobs,
files don't require any LSN synchronization logic. So, all LSN sync related operations are
skipped when the job type is METADATA. It doesn't mean it is a metadata index.

Line 29:         STOP
> STOP should be control message instead of normal replication message. Also,
ReplicationOpeartion is something submitted to the ReplicationManager and not sent to any
replica. STOP is used to inform the asynchronous replication thread to stop. Since multiple
entities submit async replication jobs to that thread and they are controlled by a queue,
STOP needs to be part of a job submitted to that queue.
I agree that STOP could be replaced by a dummy job (null value), and when that dummy job is
encountered by the thread, it would stop. However, having it like this is more readable.
Yes, stopped replication (suspended replication) can be resumed. When a replica fails, the
replication is stopped (suspended) and the replication factor is decreased. This way, newly
processed replication jobs would not expect ACK from the failed replica. After that, the replication
is resumed. Please note that this doesn't mean a replication job is stopped during the file
transfer. When a STOP job is encounter, currently ongoing replication transfers are completed
before the replication is suspended.

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Gerrit-MessageType: comment
Gerrit-Change-Id: I80565fc9d74e30440d2df5917911904ba8f33c25
Gerrit-PatchSet: 4
Gerrit-Project: hyracks
Gerrit-Branch: master
Gerrit-Owner: Murtadha Hubail <>
Gerrit-Reviewer: Ian Maxon <>
Gerrit-Reviewer: Jenkins <>
Gerrit-Reviewer: Murtadha Hubail <>
Gerrit-Reviewer: Young-Seok Kim <>
Gerrit-Reviewer: abdullah alamoudi <>
Gerrit-HasComments: Yes

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