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https://issues.apache.org/jira/browse/HBASE-4119?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13068833#comment-13068833
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Todd Lipcon commented on HBASE-4119:
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Yes, I meant locality groups as Stack described above.
The advantages of allowing multiple column families to be in a single locality
group are:
- people often want a way of grouping together sets of columns "logically" -
you can certainly use a prefix here, but the CF already seems like a natural
prefix
- often times (especially if you're new to the data model) it's not clear what
the correct grouping of columns should be for your access patterns. Putting the
different types of data in different CFs, and then later being able to migrate
CFs between locality groups allows you to do the logical groupings up front,
and then modify the physical groupings as the access patterns become more clear
later.
- BigTable has some properties that apply to column families and others that
apply to locality groups. For example, compression and block size are physical
properties and thus apply to the LG. TTL and version retention are logical
properties and thus would apply to a column family. I've often seen cases where
two types of data are stored together in a CF for locality reasons, but they
really should have different TTL policies. Another example would be schema
information for use by a coprocessor that provides a secondary index.
> Ability to add column families without disabling the table
> ----------------------------------------------------------
>
> Key: HBASE-4119
> URL: https://issues.apache.org/jira/browse/HBASE-4119
> Project: HBase
> Issue Type: Improvement
> Components: master, regionserver
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
>
> Support adding a new column family for a table without disabling the table.
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