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https://issues.apache.org/jira/browse/HBASE-565?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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stack updated HBASE-565:
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Fix Version/s: 0.2.0
Assignee: stack
Lets fix for 0.2.0. What we have just doesn't scale and its just annoying
(outputting table descriptor for every row in META scanning).
> Move Table Schema out of HRegionInfo
> ------------------------------------
>
> Key: HBASE-565
> URL: https://issues.apache.org/jira/browse/HBASE-565
> Project: Hadoop HBase
> Issue Type: Improvement
> Reporter: stack
> Assignee: stack
> Fix For: 0.2.0
>
>
> Every HRI carries a HTableDescriptor instance. When a Region context needs a
> table descriptor, doesn't have far to go. Move the HTD out of HRI and when
> wanted, go elsewhere to go get it.
> In Bigtable paper, Schema is stored over in Chubby. Could run a Zookeeper
> instance easy-enough and store it there. Would run on master. ZooKeeper
> snapshots its in-memory database to local director on disk -- not DFS. If a
> ZooKeeper cluster, then that should protect against loss. Master could tell
> regionservers the address of the zookeeper instance to use (as it does other
> vitals currently). Later we could add the indirection so zookeeper is where
> regionservers register themselves on startup and master could watch here for
> the coming and going of servers.
> Or, we could store the schema in DFS. Good thing would be replication of
> critical data and an hbasck tool could read the file to learn table schema
> (Would be awkward having to read zookeeper format out on local filesystem).
> Downside would be that any change in schema would require offlining unless we
> develop a message that the master could send regionservers to notify them of
> of minor schema changes -- e.g. flip to being memory-based or to being
> compressed or that two column families are now of a single locality group
> (Zookeeper has the watcher mechanism where regionservers could 'notice'
> schema changes).
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