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https://issues.apache.org/jira/browse/HIVE-13221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15314897#comment-15314897
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Sushanth Sowmyan commented on HIVE-13221:
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I've been intending to review this forever and not finding time to do so. Sorry
for the delay! :(
I'm a strong +1 on the intent of this patch, and would definitely like to see
it in. :)
Looking at the code itself, I'm mostly +1, I have a couple of questions
regarding the following comment:
{noformat}
// Note that this doesn't start metastore (ACID) background threads.
{noformat}
Why not?
I guess I don't yet know enough about the background ACID threads to know if
they're safe to be started across multiple instances, but I would imagine so?
(Otherwise, is there some config that keeps them from trampling on each other
if multiple HMS instances are running on a single cluster?) But if they were
safe to run on multiple instances, is there a reason we don't start them here?
If this was enabled, I can see a case wherein, for small warehouses, they only
ever run a single HS2+HMS service. I think that would be the biggest usecase
for this patch.
Also, from a brief run-through, it looks like the ACID threads are instantiated
at HMSHandler.init() time, so each HMSHandler that the metastore creates would
invoke them, would it not? So I would imagine that they're started anyway,
which confuses me. (Unless that's what you meant by saying that that doesn't
start the ACID background threads, in that that's not where they are started.)
> expose metastore APIs from HS2
> ------------------------------
>
> Key: HIVE-13221
> URL: https://issues.apache.org/jira/browse/HIVE-13221
> Project: Hive
> Issue Type: Bug
> Reporter: Sergey Shelukhin
> Assignee: Sergey Shelukhin
> Attachments: HIVE-13221.01.patch, HIVE-13221.patch
>
>
> I was always wondering why we don't do that, for the people who run HS2 and
> also need metastore due to it being used externally; they don't need to run a
> standalone metastore.
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