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HBase, mail # user - Client Get vs Coprocessor scan performance


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Re: Client Get vs Coprocessor scan performance
Ted Yu 2013-08-18, 13:39
bq. Get'ting 100 rows seems to be faster than the FuzzyRowFilter (mask on
the whole length of the key)

In this case the Get's are very selective. The number of rows FuzzyRowFilter
was evaluated against would be much higher.
It would be nice if you remember the time each took.

bq. Also, I am seeing very bad concurrent query performance

Were the multi Get's performed by your coprocessor within region boundary
of the respective coprocessor ? Just to confirm.

bq. that would make Coprocessors almost single threaded across multiple
invocations ?

Let me dig into code some more.

Cheers
On Sat, Aug 17, 2013 at 10:34 PM, Kiru Pakkirisamy <
[EMAIL PROTECTED]> wrote:

> Ted,
> On a table with 600K rows, Get'ting 100 rows seems to be faster than the
> FuzzyRowFilter (mask on the whole length of the key). I thought the
> FuzzyRowFilter's  SEEK_NEXT_USING_HINT would help.  All this on the client
> side, I have not changed my CoProcessor to use the FuzzyRowFilter based on
> the client side performance (still doing multiple get inside the
> coprocessor). Also, I am seeing very bad concurrent query performance. Are
> there any thing that would make Coprocessors almost single threaded across
> multiple invocations ?
> Again, all this after putting in 0.94.10 (for hbase-6870 sake) which seems
> to be very good in bringing up the regions online fast and balanced. Thanks
> and much appreciated.
>
> Regards,
> - kiru
>
>
> Kiru Pakkirisamy | webcloudtech.wordpress.com
>
>
> ________________________________
>  From: Ted Yu <[EMAIL PROTECTED]>
> To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
> Sent: Saturday, August 17, 2013 4:19 PM
> Subject: Re: Client Get vs Coprocessor scan performance
>
>
> HBASE-6870 targeted whole table scanning for each coprocessorService call
> which exhibited itself through:
>
> HTable#coprocessorService -> getStartKeysInRange -> getStartEndKeys ->
> getRegionLocations -> MetaScanner.allTableRegions(getConfiguration(),
> getTableName(), false)
>
> The cached region locations in HConnectionImplementation would be used.
>
> Cheers
>
>
> On Sat, Aug 17, 2013 at 2:21 PM, Asaf Mesika <[EMAIL PROTECTED]>
> wrote:
>
> > Ted, can you elaborate a little bit why this issue boosts performance?
> > I couldn't figure out from the issue comments if they execCoprocessor
> scans
> > the entire .META. table or and entire table, to understand the actual
> > improvement.
> >
> > Thanks!
> >
> >
> >
> >
> > On Fri, Aug 9, 2013 at 8:44 AM, Ted Yu <[EMAIL PROTECTED]> wrote:
> >
> > > I think you need HBASE-6870 which went into 0.94.8
> > >
> > > Upgrading should boost coprocessor performance.
> > >
> > > Cheers
> > >
> > > On Aug 8, 2013, at 10:21 PM, Kiru Pakkirisamy <
> [EMAIL PROTECTED]
> > >
> > > wrote:
> > >
> > > > Ted,
> > > > Here is the method signature/protocol
> > > > public Map<String, Double> getFooMap<String, Double> input,
> > > > int topN) throws IOException;
> > > >
> > > > There are 31 regions on 4 nodes X 8 CPU.
> > > > I am on 0.94.6 (from Hortonworks).
> > > > I think it seems to behave like what linwukang says, - it is almost a
> > > full table scan in the coprocessor.
> > > > Actually, when I set more specific ColumnPrefixFilters performance
> went
> > > down.
> > > > I want to do things on the server side because, I dont want to be
> > > sending 500K column/values to the client.
> > > > I cannot believe a single-threaded client which does some
> calculations
> > > and group-by  beats the coprocessor running in 31 regions.
> > > >
> > > > Regards,
> > > > - kiru
> > > >
> > > >
> > > > Kiru Pakkirisamy | webcloudtech.wordpress.com
> > > >
> > > >
> > > > ________________________________
> > > > From: Ted Yu <[EMAIL PROTECTED]>
> > > > To: [EMAIL PROTECTED]; Kiru Pakkirisamy <
> [EMAIL PROTECTED]
> > >
> > > > Sent: Thursday, August 8, 2013 8:40 PM
> > > > Subject: Re: Client Get vs Coprocessor scan performance
> > > >
> > > >
> > > > Can you give us a bit more information ?