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From ivakegg <>
Subject [GitHub] accumulo pull request #260: ACCUMULO-4643 initial implementation
Date Tue, 30 May 2017 15:30:27 GMT
Github user ivakegg commented on a diff in the pull request:
    --- Diff: server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/
    @@ -586,6 +589,10 @@ private LookupResult lookup(SortedKeyValueIterator<Key,Value>
mmfi, List<Range>
    +      } catch (ScanYieldException sye) {
    +        log.debug("Scan yield exception detected at position " + sye.getPosition());
    +        addUnfinishedRange(lookupResult, range, sye.getPosition(), false);
    --- End diff --
    Each key that is actually returned by the iterator will be returned to the user.  The
ScanYieldException would be thrown within the next call (presumably because it has been doing
a lot of scanning and not actually finding any keys to return).  The key placed in the exception
would where the next call left off before finding the next key to return.  All keys already
returned by getTopKey() after successfull next calls would still be returned appropriately.
    If you follow the timesUp or the exceededMemoryUsage used here, you will see that it is
essentially follows the same paradigm of yielding the scan until later.  I am just supplying
a way for the underlying iterator to force this to happen.

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