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https://issues.apache.org/jira/browse/HBASE-12016?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14140029#comment-14140029
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Andrey Stepachev commented on HBASE-12016:
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[~virag]
bq. Good for me. One minor issue is if they query the
HTableDescriptor.META_TABLEDESC for versions, will they get 3 (the default)?
Existing 0.98 deployments will have meta with 10 versions. So, should we have
10 as default for 0.98?
I think that should be done in back porting phase. I'm sure it is a good idea
to keep same value for old versions.
[~stack] Thank you for looking at the patch.
bq. Undoing the hardcoding of meta is the right way to go. I see this patch as
fine for now but imagine we could be in for some interesting times when meta
actually changes an attribute.... Lets see how it goes..
That was why I've implemented different access stories. Client side will always
go through getDescriptor(TableName.META_TABLE), so meta will have the same
method of descriptor resolution as regular tables. That gives identical
descriptors across the cluster.
For server side it is a bit awkward, because it depends on config and looks
more like static thing. I think we have to introduce, say, TableManager, and
put all tables in it (real or virtual). I'm working on proposal, but that is
out of the scope of this patch.
bq. Patch looks good to me except for the nit that meta is defined in
FSTableDescriptor rather than say in TableDescriptor. If we have another
registry implementation, it would have to copy the FSTD definition for meta?
Thank you for good suggestion! Moved.
> Reduce number of versions in Meta table. Make it configurable
> -------------------------------------------------------------
>
> Key: HBASE-12016
> URL: https://issues.apache.org/jira/browse/HBASE-12016
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 2.0.0
> Reporter: Andrey Stepachev
> Assignee: Andrey Stepachev
> Priority: Minor
> Fix For: 2.0.0, 0.98.7, 0.99.1
>
> Attachments: HBASE-12016.patch, HBASE-12016.patch
>
>
> Currently meta keeps up to 10 versions of each KV.
> For big metas it leads to substantial memory overhead and scan slowdowns.
> (see https://issues.apache.org/jira/browse/HBASE-11165 )
> Need to keep reasonable number of versions (suggested value is 3).
> Number of versions configurable via parameter: hbase.meta.versions
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