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From "Ajay Yadava (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FALCON-1059) Lineage should support bootstrapping
Date Mon, 09 Mar 2015 05:59:38 GMT

    [ https://issues.apache.org/jira/browse/FALCON-1059?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14352587#comment-14352587

Ajay Yadava commented on FALCON-1059:

[~pallavi.rao] This patch is aimed only to handle the use case where the lineage was never
enabled but now people want to use it e.g. for people who are upgrading from a previous version
where lineage is disabled to the newer version where lineage is enabled. 

It is not aimed to handle the case where lineage feature is turned on for a duration and then
turned off and then back on because IMHO that feature is not to enable toggling lineage but
to keep it backward compatible. If for some reason one has to disable lineage and then turn
it back on then they have to stop the server, nuke the graph db and then restart. Even if
you wanted to you might be able to update Entity data but you will miss all the instance data
and hence lineage will become inconsistent. Trying to recover all the instance data will be
unnecessarily complicated and excruciatingly slow.

As for startup time, this is quite the bare minimum that is required and I don't think it
will be slow, with the metrics published for query rates on graph db I think it should add
a couple of seconds in worst case, we might optimize it even more but I don't think it's worth
it at the cost of keeping the code more maintainable. 

> Lineage should support bootstrapping
> ------------------------------------
>                 Key: FALCON-1059
>                 URL: https://issues.apache.org/jira/browse/FALCON-1059
>             Project: Falcon
>          Issue Type: Improvement
>            Reporter: Ajay Yadava
>            Assignee: Ajay Yadava
>         Attachments: FALCON-1059.patch
> Lineage should support bootstrapping. Currently MetadataMappingService does nothing in
onReload( )

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