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https://issues.apache.org/jira/browse/HBASE-15398?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15187477#comment-15187477
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stack commented on HBASE-15398:
-------------------------------
Result has up to this not needed sorting. Adding it implies a new 'order' where
results coming out of server 'may' not be in order. Do we have to go here? (The
following comparator will work for user-space results only
Collections.sort(cells, CellComparator.COMPARATOR); and will give incorrect
results if applied to meta emissions)
Would be good to avoid decorating ClientScanner w/ an attribute that is set
when a particular filter is in use or adding to Scan a method that is looking
for a particular filter only... ditto for special-handling in HRegion.
Not chunking results is not an option.
If the optional filter SVCF breaks expectiations lets remove it until its fixed
rather than pull around our workings to suit its brokenness.
Thanks for working on this [~yangzhe1991]
> Cells loss or disorder when using family essential filter and partial
> scanning protocol
> ---------------------------------------------------------------------------------------
>
> Key: HBASE-15398
> URL: https://issues.apache.org/jira/browse/HBASE-15398
> 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: 15398-test.txt, HBASE-15398-v2.patch, HBASE-15398.v1.txt
>
>
> In RegionScannerImpl, we have two heaps, storeHeap and joinedHeap. If we have
> a filter and it doesn't apply to all cf, the stores whose families needn't be
> filtered will be in joinedHeap. We scan storeHeap first, then joinedHeap,
> and merge the results and sort and return to client. We need sort because the
> order of Cell is rowkey/cf/cq/ts and a smaller cf may be in the joinedHeap.
> However, after HBASE-11544 we may transfer partial results when we get
> SIZE_LIMIT_REACHED_MID_ROW or other similar states. We may return a larger cf
> first because it is in storeHeap and then a smaller cf because it is in
> joinedHeap. Server won't hold all cells in a row and client doesn't have a
> sorting logic. The order of cf in Result for user is wrong.
> And a more critical bug is, if we get a LIMIT_REACHED_MID_ROW on the last
> cell of a row in storeHeap, we will break scanning in RegionScannerImpl and
> in populateResult we will change the state to SIZE_LIMIT_REACHED because next
> peeked cell is next row. But this is only the last cell of one and we have
> two... And SIZE_LIMIT_REACHED means this Result is not partial (by
> ScannerContext.partialResultFormed), client will see it and merge them and
> return to user with losing data of joinedHeap. On next scan we will read next
> row of storeHeap and joinedHeap is forgotten and never be read...
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