Github user ivakegg commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/260#discussion_r119133690
--- Diff:
server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java ---
@@ -586,6 +589,10 @@ private LookupResult
lookup(SortedKeyValueIterator<Key,Value> mmfi, List<Range>
mmfi.next();
}
+ } 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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