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https://issues.apache.org/jira/browse/HBASE-4213?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13103925#comment-13103925
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Subbu M Iyer commented on HBASE-4213:
-------------------------------------
Based on further discussions, here are some call outs:
1. Provide separate public API's for alter instant operations so as to not
break existing public API's with out deprecation or prior notice.
2. Provide a config level setting to enable instant schema update feature.
(defaults to false). This will also enable us to release this feature in a more
controlled and transparent manner.
3. We don't want to intimidate developers with scary boolean flags
that does things in a such a way that they may not completely
understand or care about.
4.
Providing a developer level API to use instant-alter is good in the
sense they can fully capitalize a scalable/fault tolerant variants. At
the same time it might be confusing to some in the sense that why we
are even providing a "not scalable/fault tolerant" variant in the
first place.
5. We don't want to expose implementation details such as "this flag
uses ZK to track schema changes and so on"
So, long story short:
In addition to review comments, V7 will include the following:
1. Add new config parameter "hbase.instant.schema.change.enabled"
(exact name of flag is open) and default to "false" so that all
existing API's will go over the current path untouched.
2. Separate public API's for all alter operations which supports the
new pattern in addition to existing public API's. New API's will take
in a boolean parameter that overrides the config setting on a per
request basis.
3. Internally both the API's will go through the same pipeline to
promote reuse as well as maintainability.
Please let me know your thoughts/comments.
> Support for fault tolerant, instant schema updates with out master's
> intervention (i.e with out enable/disable and bulk assign/unassign) through
> ZK.
> ----------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-4213
> URL: https://issues.apache.org/jira/browse/HBASE-4213
> Project: HBase
> Issue Type: Improvement
> Reporter: Subbu M Iyer
> Assignee: Subbu M Iyer
> Fix For: 0.92.0
>
> Attachments: 4213-Instant_Schema_change_through_ZK.patch,
> 4213-V5-Support_instant_schema_changes_through_ZK.patch, 4213.v6,
> HBASE-4213-Instant_schema_change.patch,
> HBASE-4213_Instant_schema_change_-Version_2_.patch,
> HBASE_Instant_schema_change-version_3_.patch
>
>
> This Jira is a slight variation in approach to what is being done as part of
> https://issues.apache.org/jira/browse/HBASE-1730
> Support instant schema updates such as Modify Table, Add Column, Modify
> Column operations:
> 1. With out enable/disabling the table.
> 2. With out bulk unassign/assign of regions.
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