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https://issues.apache.org/jira/browse/HBASE-3434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12979841#action_12979841
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stack commented on HBASE-3434:
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(No worries regards blue-skying Dhruba... go for it).
If we did not want to alter the fundamentals of HBase, Collections might be
done as a Coprocessor instance. Coprocessors have hooks pre/post Get as well
as on flush/compact. You'd mark the region to load KeyCollectionCoprocessor.
The KCCP would work on ColumnFamilies marked as KeyCollections either of type
increment or type List. On flush, we'd write out the aggregating Tombstone (We
want to avoid data bloat if we can -- just don't put it into the FS beyond the
WAL). On Get, we'd aggregate until we hit a tombstone writing back a new
tombstone record if "too many" deltas have gone in since the last tombstone.
Having all this KeyCollection code cohere inside a Coprocessor is a nice way of
keeping the code all together rather than spread about the server.
Otherwise, we could make a HCD as carrying Collections only and then have the
server do extra processing on Get, flush, compact if the HCD is of this type.
If the marking was done as a special KV Type, then we could have Collections
live in the same family as plain KVs, if we wanted to do such a thing (I don't
think we do especially if the write-rate of increments is high).
> ability to increment a counter without reading original value from storage
> --------------------------------------------------------------------------
>
> Key: HBASE-3434
> URL: https://issues.apache.org/jira/browse/HBASE-3434
> Project: HBase
> Issue Type: Improvement
> Components: client, regionserver
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
>
> There are a bunch of applications that do read-modify-write operations on
> HBase constructs, e.g a counter; The counter value has to be read in from
> hdfs before it can be incremented. We have an application where the number
> of increments on a counter far outnumbers the number of times the counter is
> used or read. For these type of applications, it will be very beneficial to
> not have to read in the counter from disk before it can be incremented.
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