[
https://issues.apache.org/jira/browse/HBASE-9794?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Andrew Kyle Purtell resolved HBASE-9794.
----------------------------------------
Resolution: Won't Fix
> KeyValues / cells backed by buffer fragments
> --------------------------------------------
>
> Key: HBASE-9794
> URL: https://issues.apache.org/jira/browse/HBASE-9794
> Project: HBase
> Issue Type: Brainstorming
> Affects Versions: 0.98.0
> Reporter: Andrew Kyle Purtell
> Priority: Major
>
> There are various places in the code where we see comments to the effect
> "would be great if we had a scatter gather API for KV", appearing at places
> where we rewrite KVs on the server, for example in HRegion where we process
> appends and increments.
> KeyValues are stored in buffers of fixed length. This approach has
> performance advantages for the common case where KVs are not manipulated on
> their way from disk to RPC. The disadvantage of this approach is any
> manipulation of the KV internals then requires the creation of a new buffer
> to hold the result, and a copy of the KV data into the new buffer. Appends
> and increments are typically a small percentage of overall workload so this
> has been fine up to now.
>
> KeyValues can now carry metadata known as tags. Tags are stored contiguously
> with the rest of the KeyValue. Applications wishing to use tags (like per
> cell security) change the equation by wanting to rewrite KVs significantly
> more often.
> We should consider backing KeyValue with an alternative structure that can
> better support rewriting portions of its data, appends to existing buffers,
> scatter-gather copies, possibly even copy-on-write.
--
This message was sent by Atlassian Jira
(v8.20.7#820007)
