Lars Hofhansl created HBASE-10625:
-------------------------------------
Summary: Remove unnecessary key compare from
AbstractScannerV2.reseekTo
Key: HBASE-10625
URL: https://issues.apache.org/jira/browse/HBASE-10625
Project: HBase
Issue Type: Bug
Reporter: Lars Hofhansl
Attachments: 10625-0.94.txt
In reseekTo we find this
{code}
...
compared = compareKey(reader.getComparator(), key, offset, length);
if (compared < 1) {
// If the required key is less than or equal to current key, then
// don't do anything.
return compared;
} else {
...
return loadBlockAndSeekToKey(this.block, this.nextIndexedKey,
false, key, offset, length, false);
...
{code}
loadBlockAndSeekToKey already does the right thing when a we pass a key that
sorts before the current key. It's less efficient than this early check, but in
the vast (all?) cases we pass forward keys (as required by the reseek
contract). We're optimizing the wrong thing.
Scanning with the ExplicitColumnTracker is 20-30% faster.
(I tested with rows of 5 short KVs selected the 2nd and or 4th column)
I propose simply removing that check.
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