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https://issues.apache.org/jira/browse/HBASE-1219?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12680659#action_12680659
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Jim Kellerman commented on HBASE-1219:
--------------------------------------
In TestScanner, the code:
{code}
} catch (Exception e) {
LOG.error("Failed test because of ...", e);
{code}
doesn't seem to let the exception and does not call fail(). Should it?
Spelling:
HStoreScanner:235:
{code}
LOG.info("RMOEVE CLOSING NEXT " + i);
{code}
HStoreScanner:250:
{code}
LOG.info("RMOEVE CLOSING ADVANCING " + i);
{code}
HStoreScanner:280:
{code}
LOG.info("RMOEVE CLOSING " + i);
{code}
Otherwise, +1 (a little hard to grasp all of what's going on, but scanners take
time to get your head around anyway. I wouldn't
hold that against this patch)
> Scanners can miss values riding the flush transition
> ----------------------------------------------------
>
> Key: HBASE-1219
> URL: https://issues.apache.org/jira/browse/HBASE-1219
> Project: Hadoop HBase
> Issue Type: Bug
> Reporter: stack
> Priority: Blocker
> Fix For: 0.19.1, 0.20.0
>
> Attachments: 1219.patch
>
>
> A scanner is made of a memcache scanner and a store files scanner. When a
> flush happens, the memcache content gets turned into a store file and is
> added to the list of already existing scanners. Currently the two scanners
> run autonomously. Ben Maurer points out that if we were returning values out
> of the memcache because they were of lower value than store file content, the
> lower pegging that was going on in memcache doesn't make it across when we
> pick up the memcache values in the flushed store file; we just keep on with
> whatever the lowest among the store files that were in place before the flush.
> Its a hard one to spot but should be easy to make a test for it.
> Ben Maurer also points out that in StoreFileScanner, we should not register
> the observer until after the scanners have been setup:
> {code}
> public StoreFileScanner(final Store store, final long timestamp,
> final byte [][] targetCols, final byte [] firstRow)
> throws IOException {
> super(timestamp, targetCols);
> this.store = store;
> this.store.addChangedReaderObserver(this);
> try {
> openScanner(firstRow);
> ...
> {code}
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