[
https://issues.apache.org/jira/browse/HBASE-3434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12979816#action_12979816
]
dhruba borthakur commented on HBASE-3434:
-----------------------------------------
hi stack, Some of these ideas are still raw in my brain, so please excuse me
if my writeup is not very coherant.
There are two ways to mark these new records. One way is to have a new value
for KeyValue.Type.Collection. The other option is to have a new field in
HColumnDescriptor to say that all columns in that family are of Collection
type. Do you have a preference (and why)? The two different types of collection
to start with can be Counters and Lists.
A cell that has the aggregated value is a TombStone (no scans need to go beyond
that). A cell that does not have an aggregated value is called a Delta cell. A
KeyCollection is made of Kvs. The precise-type of collection (whether Counters,
List, etc) is stored in the Value itself.
There are two triggers that merge of set of Deltas cells to create a TombStone
cell. First, a major compaction thread aggregates Deltas into Tombstones.
Secondly, when an application makes a Get() call, it aggregates on demand and
stores a TombStone.
> 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.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
