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https://issues.apache.org/jira/browse/HBASE-13387?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14488008#comment-14488008
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stack commented on HBASE-13387:
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bq. Adding one more cell and allowing the user to to manipulate the cell using
instance of check - so it becomes mandatory that he uses this instance of check
or use the CellUtil. Another thing is it becomes user's prudency to use the
correct Offset API like use getXXXOffset for getXXXArray and use the
getBBPosition() for the getXXXBuffer.
I cannot parse the above. Please rephrase.
bq. This problem was already there in terms of using hasArray without which he
would get an UnSupportedException but did not have the problem of the API
confusion.
Not sure what above is referring to. Yes, we have an issue where a cell
implementation wants to change the read path implementation to suit. Yes, if a
cell implementation takes the wrong path, it should blowup and throw an
exception. Which API confusion? (What Cell methods do when BB-backed or the
change of all APIs to take a ServerCell?)
bq. 'instanceOf' and 'typecast' would become mandatory because in our previous
patches we had this way and later reverted this as things look ugly
particularly because the number of times we call different comparators is huge.
To be clear, what is being advocated now is corralling locations where have to
do instanceof into a few areas only rather than all over the readpath with a
follow-on project to see if we could avoid instanceof by using factories' to
load type-appropriate 'read-paths': e.g. a DBB aware comparator in place of
current one if RS is running offheap read path.
bq. One more thing, I think in these implementations it is very much mandatory
that we cache these new offsets and lengths ? Am i right?
The constant reparse and recalc of lengths and offsets costs. Caching this
stuff is secondary I'd say, an implementation detail as [~anoop.hbase] called
it earlier.
> Add ServerCell an extension to Cell
> -----------------------------------
>
> Key: HBASE-13387
> URL: https://issues.apache.org/jira/browse/HBASE-13387
> Project: HBase
> Issue Type: Sub-task
> Components: regionserver, Scanners
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Attachments: WIP_HBASE-13387_V2.patch, WIP_ServerCell.patch
>
>
> This came in btw the discussion abt the parent Jira and recently Stack added
> as a comment on the E2E patch on the parent Jira.
> The idea is to add a new Interface 'ServerCell' in which we can add new
> buffer based getter APIs, hasArray API etc. We will keep this interface
> @InterfaceAudience.Private
> Also we have to change the timestamp and seqId on Cells in server side. We
> have added new interfaces SettableSequenceId, SettableTimestamp for this. Now
> if we can add a ServerCell we can add the setter APIs there.
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