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https://issues.apache.org/jira/browse/HBASE-19001?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16207640#comment-16207640
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Duo Zhang edited comment on HBASE-19001 at 10/17/17 1:34 PM:
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I plan to implement an example of the write-heavy increment where we convert
increment to a put and aggregate the puts when get/flush/compaction. It will be
a good example to show how to use the new CP hooks. In HBASE-19002, maybe.
was (Author: apache9):
I plan to implement an example of the write-heavy increment where we convert
increment to a put and aggregate the puts when get/flush/compaction. It will be
a good example to show how to use the new CP hooks.
> Remove the hooks in RegionObserver which are designed to construct a
> StoreScanner which is marked as IA.Private
> ---------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-19001
> URL: https://issues.apache.org/jira/browse/HBASE-19001
> Project: HBase
> Issue Type: Sub-task
> Components: Coprocessors
> Reporter: Duo Zhang
> Assignee: Duo Zhang
> Fix For: 2.0.0-alpha-4
>
> Attachments: HBASE-19001-v1.patch, HBASE-19001-v2.patch,
> HBASE-19001.patch
>
>
> There are three methods here
> {code}
> KeyValueScanner
> preStoreScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
> Store store, Scan scan, NavigableSet<byte[]> targetCols,
> KeyValueScanner s, long readPt)
> throws IOException;
> InternalScanner
> preFlushScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
> Store store, List<KeyValueScanner> scanners, InternalScanner s, long
> readPoint)
> throws IOException;
> InternalScanner
> preCompactScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
> Store store, List<? extends KeyValueScanner> scanners, ScanType
> scanType, long earliestPutTs,
> InternalScanner s, CompactionLifeCycleTracker tracker,
> CompactionRequest request,
> long readPoint) throws IOException;
> {code}
> For the flush and compact ones, we've discussed many times, it is not safe to
> let user inject a Filter or even implement their own InternalScanner using
> the store file scanners, as our correctness highly depends on the complicated
> logic in SQM and StoreScanner. CP users are expected to wrap the original
> InternalScanner(it is a StoreScanner anyway) in preFlush/preCompact methods
> to do filtering or something else.
> For preStoreScannerOpen it even returns a KeyValueScanner which is marked as
> IA.Private... This is less hurt but still, we've decided to not expose
> StoreScanner to CP users so here this method is useless. CP users can use
> preGetOp and preScannerOpen method to modify the Get/Scan object passed in to
> inject into the scan operation.
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