Grokbase Groups HBase user June 2012
FAQ
0.90.4-cdh3u3 is the version I'm running.

~Jeff
On 6/27/2012 5:50 PM, Ted Yu wrote:
I created HBASE-6287 <https://issues.apache.org/jira/browse/HBASE-6287> for porting HBASE-5941 to
trunk.

Jeff:
What version of HBase are you using ?

Since HBASE-5941 is an improvement, a vote may be raised for porting it to other branches.

On Wed, Jun 27, 2012 at 4:15 PM, Jeff Whiting wrote:

Looking at HBASE-6284 it seems that deletes are not batched at the regionserver level so that
is the reason for the performance degradation. Additionally HBASE-5941 with the locks is also
contributing to the performance degradation.

So until those changes get into an hbase release I just have to live with the slower
performance. Is there anything I need to do on my end?

Just as a sanity check, I tried setting a timestamp in the delete object but it made no
difference. I'll batch my deletes at end as you suggested (as memory allows).

Thanks,
~Jeff

On 6/27/2012 4:11 PM, Ted Yu wrote:

Amit:
Can you point us to the JIRA or changelist in 0.89-fb ?

Thanks


On Wed, Jun 27, 2012 at 3:05 PM, Amitanand Aiyer wrote:

There was some difference in the way locks are taken for batched deletes
and puts. This was fixed for 89.

I wonder if the same could be the issue here.

Sent from my iPhone

On Jun 27, 2012, at 2:04 PM, "Jeff Whiting" wrote:

I'm struggling to understand why my deletes are taking longer than my

inserts. My understanding is that a delete is just an insertion of a
tombstone. And I'm deleting the entire row.

I do a simple loop (pseudo code) and insert the 100 byte rows:

for (int i=0; i < 50000; i++)
{
puts.append(new Put(rowkey[i], oneHundredBytes[i]));

if (puts.size() % 1000 == 0)
{
Benchmark.start();
table.batch(puts);
Benchmark.stop();
}
}


The above takes about 8282ms total.

However the delete takes more than twice as long:

Iterator it = table.getScannerScan(rowkey[0],

rowkey[50000-1]).iterator();

while(it.hasNext())
{
r = it.next();
deletes.append(new Delete(r.getRow()));
if (deletes.size() % 1000 == 0)
{
Benchmark.start();
table.batch(deletes);
Benchmark.stop();
}
}

The above takes 17369ms total.

I'm only benchmarking the deletion time and not the scan time.

Additionally if I batch the deletes into one big one at the end (rather
than while I'm scanning) it takes about the same amount of time. I am
deleting the entire row so I wouldn't think it would be doing a read before
the delete (
http://mail-archives.apache.org/mod_mbox/hbase-user/201206.mbox/%3CE83D30E8F408F94A96F992785FC29D82063395D6@s2k3mntaexc1.mentacapital.local%3E
).

Any thoughts on why it is slower and how I can speed it up?

Thanks,
~Jeff

--
Jeff Whiting
Qualtrics Senior Software Engineer
jeffw@qualtrics.com

--
Jeff Whiting
Qualtrics Senior Software Engineer
jeffw@qualtrics.com

--
Jeff Whiting
Qualtrics Senior Software Engineer
jeffw@qualtrics.com

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postedJun 27, '12 at 9:04p
activeJun 28, '12 at 2:38p
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