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From Ted Yu <yuzhih...@gmail.com>
Subject Re: Coprocessor Aggregation supposed to be ~20x slower than Scans?
Date Tue, 15 May 2012 17:47:49 GMT
Take your time.
Once you complete your first submission, subsequent contributions would be
easier.

On Tue, May 15, 2012 at 10:34 AM, anil gupta <anilgupta84@gmail.com> wrote:

> Hi Ted,
>
> I created the jira:https://issues.apache.org/jira/browse/HBASE-5999 for
> fixing this.
>
> Creating the patch might take me sometime(due to learning curve) as this is
> the first time i would be creating a patch.
>
> Thanks,
> Anil Gupta
>
>
> On Mon, May 14, 2012 at 4:00 PM, Ted Yu <yuzhihong@gmail.com> wrote:
>
> > I was aware of the following change.
> >
> > Can you log a JIRA and attach the patch to it ?
> >
> > Thanks for trying out and improving aggregation client.
> >
> > On Mon, May 14, 2012 at 3:31 PM, anil gupta <anilgupta84@gmail.com>
> wrote:
> >
> > > Hi Ted,
> > >
> > > If we change the if statement condition in validateParameters method in
> > > AggregationClient.java to:
> > > if (scan == null || (Bytes.equals(scan.getStartRow(),
> scan.getStopRow())
> > &&
> > > !Bytes.equals(scan.getStartRow(), HConstants.EMPTY_START_ROW)) ||
> > > (Bytes.compareTo(scan.getStartRow(), scan.getStopRow()) > 0 &&
> > > *!Bytes.equals(scan.getStopRow(),
> > > HConstants.EMPTY_END_ROW)* ))
> > >
> > > Condition specified in the bold and Italic will handle the case when
> the
> > > stopRow is not specified. IMHO, it's not an error if we are not
> > specifying
> > > the stopRow. This is what is was looking for because in my case i didnt
> > > wanted to set the stop row as I am using a prefix filter. I have tested
> > the
> > > above specified code and it works fine when i only specify the
> startRow.
> > Is
> > > this a desirable functionality? If yes, should this be added to trunk?
> > >
> > > Here is the link for source of AggregationClient:
> > >
> > >
> >
> http://grepcode.com/file_/repo1.maven.org/maven2/org.apache.hbase/hbase/0.92.0/org/apache/hadoop/hbase/client/coprocessor/AggregationClient.java/?v=source
> > >
> > > Thanks,
> > > Anil Gupta
> > >
> > >
> > > On Mon, May 14, 2012 at 1:58 PM, Ted Yu <yuzhihong@gmail.com> wrote
> > >
> > > > Anil:
> > > > As code #3 shows, having stopRow helps narrow the range of rows
> > > > participating in aggregation.
> > > >
> > > > Do you have suggestion on how this process can be made more
> > > user-friendly ?
> > > >
> > > > Thanks
> > > >
> > > > On Mon, May 14, 2012 at 1:47 PM, anil gupta <anilgupta84@gmail.com>
> > > wrote:
> > > >
> > > > > HI Ted,
> > > > >
> > > > > My bad, i missed out a big difference between the Scan object i am
> > > using
> > > > in
> > > > > my filter and Scan object used in coprocessors. So, scan object is
> > not
> > > > > same.
> > > > > Basically, i am doing filtering on the basis of a prefix of RowKey.
> > > > >
> > > > > So, in my filter i do this to build scanner:
> > > > > Code 1:
> > > > >  Filter filter = new PrefixFilter(Bytes.toBytes(strPrefix));
> > > > >            Scan scan = new Scan();
> > > > >            scan.setFilter(filter);
> > > > >            scan.setStartRow(Bytes.toBytes(strPrefix)); // I dont
> set
> > > any
> > > > > stopRow in this scanner.
> > > > >
> > > > > In coprocessor, i do the following for scanner:
> > > > > Code 2:
> > > > >  Scan scan = new Scan();
> > > > > scan.setFilter(new PrefixFilter(Bytes.toBytes(prefix)));
> > > > >
> > > > >  I dont have startRow in above code because if i only use only the
> > > > startRow
> > > > > in coprocessor scanner then i get the following exception(due to
> > this I
> > > > > removed the startRow from CP scan object code):
> > > > > java.io.IOException: Agg client Exception: Startrow should be
> smaller
> > > > than
> > > > > Stoprow
> > > > >    at
> > > > >
> > > > >
> > > >
> > >
> >
> org.apache.hadoop.hbase.client.coprocessor.AggregationClient.validateParameters(AggregationClient.java:116)
> > > > >    at
> > > > >
> > > > >
> > > >
> > >
> >
> org.apache.hadoop.hbase.client.coprocessor.AggregationClient.max(AggregationClient.java:85)
> > > > >    at
> > > > >
> > com.intuit.ihub.hbase.poc.DummyClass.doAggregation(DummyClass.java:81)
> > > > >    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> > > > >    at
> > > > >
> > > > >
> > > >
> > >
> >
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> > > > >
> > > > >
> > > > > I modified the above code#2 to add the stopRow also:
> > > > > Code 3:
> > > > > Scan scan = new Scan();
> > > > >        scan.setStartRow(Bytes.toBytes(prefix));
> > > > >
> > > > >
> > >
> scan.setStopRow(Bytes.toBytes(String.valueOf(Long.parseLong(prefix)+1)));
> > > > >        scan.setFilter(new PrefixFilter(Bytes.toBytes(prefix)));
> > > > >
> > > > > When, i run the coprocessor with Code #3, its blazing fast. I gives
> > the
> > > > > result in around 200 millisecond. :)
> > > > > Since, this was just testing a coprocessors i added the logic to
> add
> > > the
> > > > > stopRow manually. What is the reason that Scan object in
> coprocessor
> > > > always
> > > > > requires stopRow along with startRow?(code #1 works fine even when
> i
> > > dont
> > > > > use stopRow)  Can this restriction be relaxed?
> > > > >
> > > > > Thanks,
> > > > > Anil Gupta
> > > > >
> > > > >
> > > > >
> > > > > On Mon, May 14, 2012 at 12:55 PM, Ted Yu <yuzhihong@gmail.com>
> > wrote:
> > > > >
> > > > > > Anil:
> > > > > > I think the performance was related to your custom filter.
> > > > > >
> > > > > > Please tell us more about the filter next time.
> > > > > >
> > > > > > Thanks
> > > > > >
> > > > > > On Mon, May 14, 2012 at 12:31 PM, anil gupta <
> > anilgupta84@gmail.com>
> > > > > > wrote:
> > > > > >
> > > > > > > HI Stack,
> > > > > > >
> > > > > > > I'll look into Gary Helming post and try to do profiling
of
> > > > coprocessor
> > > > > > and
> > > > > > > share the results.
> > > > > > >
> > > > > > > Thanks,
> > > > > > > Anil Gupta
> > > > > > >
> > > > > > > On Mon, May 14, 2012 at 12:08 PM, Stack <stack@duboce.net>
> > wrote:
> > > > > > >
> > > > > > > > On Mon, May 14, 2012 at 12:02 PM, anil gupta <
> > > > anilgupta84@gmail.com>
> > > > > > > > wrote:
> > > > > > > > > I loaded around 70 thousand 1-2KB records in
HBase. For
> > scans,
> > > > with
> > > > > > my
> > > > > > > > > custom filter i am able to get 97 rows in 500
milliseconds
> > and
> > > > for
> > > > > > > doing
> > > > > > > > > sum, max, min(in built aggregations of HBase)
on the same
> > > custom
> > > > > > filter
> > > > > > > > its
> > > > > > > > > taking 11000 milliseconds. Does this mean that
coprocessors
> > > > > > aggregation
> > > > > > > > is
> > > > > > > > > supposed to be around ~20x slower than scans?
Am i missing
> > any
> > > > > trick
> > > > > > > over
> > > > > > > > > here?
> > > > > > > > >
> > > > > > > >
> > > > > > > > That seems like a high tax to pay for running CPs.
 Can you
> dig
> > > in
> > > > on
> > > > > > > > where the time is being spent?  (See another recent
note on
> > this
> > > > list
> > > > > > > > or on dev where Gary Helmling talks about how he did
basic
> > > > profiling
> > > > > > > > of CPs).
> > > > > > > > St.Ack
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > --
> > > > > > > Thanks & Regards,
> > > > > > > Anil Gupta
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Thanks & Regards,
> > > > > Anil Gupta
> > > > >
> > > >
> > >
> > >
> > >
> > > --
> > > Thanks & Regards,
> > > Anil Gupta
> > >
> >
>
>
>
> --
> Thanks & Regards,
> Anil Gupta
>

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