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https://issues.apache.org/jira/browse/HBASE-15325?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15184731#comment-15184731
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Anoop Sam John commented on HBASE-15325:
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{quote}
eg. if client receives 3+5+3 cells in three rpc requests, we should return
5+5+1 cells per batch to user, all of them is not partial, right?
What we should guarantee when user setAllowPartial and setBatch? If user get
three results 3+5+3, is the second result partial? Is the last one partial? And
what we should guarantee in the last partial result when user setAllowPartial
only? Now the last one is true if I am not wrong.
{quote}
Good Qs..
Yes am also +1 for returning 5+5+1 when setAllowPartial = false. (As per ur
eg:).. So here no Q of partial flag
Now coming to case where setAllowPartial = true.. It is complicated now :-)
I think we can make like mark 1st Result (3 cells) as partial. Second is not
partial when we consider that alone. And obviously last one is any way not
partial. This is how we see the results. I mean the HBase client see the
results.
When it is sent to use app level he may have to work on these and adjust the
partial flags.. It depends on how he will handle the partial results. If he
want to merge partial on his end, we mark 1st one as partial means he know he
has to wait for next Result. This comes with 5 (and so we mark it as full). So
he will take 2 cells from that and merge with 1st. So at this moment the 2nd
Result becomes partial and so he know we has to see the 3rd result and merge
it. As that is the last Result he completes the things there.
But he specified setPartial to true.. Which means he may be consuming the
results like how it comes. Or else he could have give setPartial false only?
So from HBase client side, we can follow this way of setting the flag IMHO. I
believe already we will be doing this way.
> ResultScanner allowing partial result will miss the rest of the row if the
> region is moved between two rpc requests
> -------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-15325
> URL: https://issues.apache.org/jira/browse/HBASE-15325
> Project: HBase
> Issue Type: Bug
> Components: dataloss, Scanners
> Affects Versions: 1.2.0, 1.1.3
> Reporter: Phil Yang
> Assignee: Phil Yang
> Priority: Critical
> Attachments: 15325-test.txt, HBASE-15325-v1.txt, HBASE-15325-v2.txt,
> HBASE-15325-v3.txt, HBASE-15325-v5.txt, HBASE-15325-v6.1.txt,
> HBASE-15325-v6.2.txt, HBASE-15325-v6.3.txt, HBASE-15325-v6.4.txt,
> HBASE-15325-v6.5.txt, HBASE-15325-v6.txt
>
>
> HBASE-11544 allow scan rpc return partial of a row to reduce memory usage for
> one rpc request. And client can setAllowPartial or setBatch to get several
> cells in a row instead of the whole row.
> However, the status of the scanner is saved on server and we need this to get
> the next part if there is a partial result before. If we move the region to
> another RS, client will get a NotServingRegionException and open a new
> scanner to the new RS which will be regarded as a new scan from the end of
> this row. So the rest cells of the row of last result will be missing.
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