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https://issues.apache.org/jira/browse/HBASE-12233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16582343#comment-16582343
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stack commented on HBASE-12233:
-------------------------------
Was looking at this anew today:
* We'd bring back root because we need to be able to split meta to distribute
loading, allow meta to get much bigger because more regions (scaling) and we
want to add more meta info per region (files in a region, etc.)
* All to do w/ meta is currently hardcoded; the meta table schema and the meta
first regioninfo. This would have to change if we were to allow a split meta.
The meta table descriptor is not kept anywhere but in code (user-space table
descriptors are in the filesystem). Meta table is echoed out to the filesystem
but never read from there. Ditto RegionInfo.
* Another hardcoding is that the meta table regions are hardcoded OPEN. That
would have to change too allowing offline of regions as they split.
* New clients would look for a new root znode. It'd point to a root table, a
table that would never split. It'd have the list of meta regions as it did in
the past. We'd try and avoid mistakes of the past regards stuff like key scheme
and wacky comparator to interpret it. We'd not disturb the current meta znodes.
* We'd revamp codebase so for example new clients went via root to find meta
table.
* Old clients would go looking for the single hard-coded meta region. We'd
point them at any RS or even at the Master. On each there'd be a facade that
proxied requests for the hardcoded meta region forwarding them on to actual
meta table. Might work.
* Startup would assign root first, and so on. Might work now we have AMv2 and
its startup has been cleaned up recently.
Bit of work here. Will write up a page if do more on this.
> Bring back root table
> ---------------------
>
> Key: HBASE-12233
> URL: https://issues.apache.org/jira/browse/HBASE-12233
> Project: HBase
> Issue Type: Sub-task
> Reporter: Virag Kothari
> Assignee: Virag Kothari
> Priority: Major
> Attachments: HBASE-12233.patch
>
>
> First step towards splitting meta.
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