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https://issues.apache.org/jira/browse/HBASE-6427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13424458#comment-13424458
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Lars Hofhansl commented on HBASE-6427:
--------------------------------------
After reviewing all the use cases I have this seems to be best proposal:
* add these
{code}
void postFlush(final ObserverContext<RegionCoprocessorEnvironment> c, final
Store store, final StoreFile resultFile) throws IOException;
InternalScanner preFlush(final ObserverContext<RegionCoprocessorEnvironment> c,
final Store store, final InternalScanner scanner) throws IOException;
InternalScanner preFlushScannerOpen(final
ObserverContext<RegionCoprocessorEnvironment> c, final Store store, final
KeyValueScanner memstoreScanner, final InternalScanner s) throws IOException;
InternalScanner preCompactScannerOpen(final
ObserverContext<RegionCoprocessorEnvironment> c, final Store store, List<?
extends KeyValueScanner> scanners, final ScanType scanType, final long
earliestPutTs, final InternalScanner s) throws IOException;
KeyValueScanner preStoreScannerOpen(final
ObserverContext<RegionCoprocessorEnvironment> c, final Store store, final Scan
scan, final NavigableSet<byte[]> targetCols, final KeyValueScanner s) throws
IOException;
{code}
* deprecate these:
{code}
void postFlush(final ObserverContext<RegionCoprocessorEnvironment> c) throws
IOException;
void preFlush(final ObserverContext<RegionCoprocessorEnvironment> c) throws
IOException;
{code}
The new {pre|post}Flush are called per Store in analogy to {pre|post}Compact.
pre{Flush|Compact}ScannerOpen are called before the flush/compaction scanner is
built.
This is give maximum flexibility (I can control the reading scanners *and* how
the storefiles are written for both flushes and compactions), makes more sense
of {pre|post}Flush and leave existing functionality in place.
This is the first proposal that really "feels" right to me. I'll have a patch
for that soon.
> Pluggable compaction policies via coprocessors
> ----------------------------------------------
>
> Key: HBASE-6427
> URL: https://issues.apache.org/jira/browse/HBASE-6427
> Project: HBase
> Issue Type: New Feature
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Priority: Minor
> Attachments: 6427-notReady.txt, 6427-v1.txt, 6427-v2.txt,
> 6427-v3.txt, 6427-v4.txt, 6427-v5.txt
>
>
> When implementing higher level stores on top of HBase it is necessary to
> allow dynamic control over how long KVs must be kept around.
> Semi-static config options for ColumnFamilies (# of version or TTL) is not
> sufficient.
> This can be done with a few additional coprocessor hooks, or by makeing
> Store.ScanInfo pluggable.
> Was:
> The simplest way to achieve this is to have a pluggable class to determine
> the smallestReadpoint for Region. That way outside code can control what KVs
> to retain.
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