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Subject: Re: Read Latency
From: aaron morton <aaron@thelastpickle.com>
In-Reply-To: <AANLkTimpL475-DrecqZeBVs233H_-188KUGfDr7av9-=@mail.gmail.com>
Date: Wed, 20 Oct 2010 07:06:30 +1300
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To: user@cassandra.apache.org

Wayne,=20
I'm calling cassandra from Python and have not seen too many 3 second =
reads.=20

Your last email with log messages in it looks like your are asking for =
10,000,000 columns. How much data is this request actually transferring =
to the client? The column names suggest only a few.=20

DEBUG [pool-1-thread-64] 2010-10-18 19:25:28,867 StorageProxy.java (line =
471) strongread reading data for SliceFromReadCommand(table=3D'table', =
key=3D'key1', column_parent=3D'QueryPath(columnFamilyName=3D'fact', =
superColumnName=3D'null', columnName=3D'null')', start=3D'503a', =
finish=3D'503a7c', reversed=3Dfalse, count=3D10000000) from 698@/x.x.x.6

Aaron

On 20 Oct 2010, at 06:18, Jonathan Ellis wrote:

> I would expect C++ or Java to be substantially faster than Python.
> However, I note that Hector (and I believe Pelops) don't yet use the
> newest, fastest Thrift library.
>=20
> On Tue, Oct 19, 2010 at 8:21 AM, Wayne <wav100@gmail.com> wrote:
>> The changes seems to do the trick. We are down to about 1/2 of the =
original
>> quorum read performance. I did not see any more errors.
>>=20
>> More than 3 seconds on the client side is still not acceptable to us. =
We
>> need the data in Python, but would we be better off going through =
Java or
>> something else to increase performance? All three seconds are taken =
up in
>> Thrift itself (fastbinary.decode_binary(self, iprot.trans, =
(self.__class__,
>> self.thrift_spec))) so I am not sure what other options we have.
>>=20
>> Thanks for your help.
>>=20
>=20
>=20
>=20
> --=20
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com