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From aaron morton <aa...@thelastpickle.com>
Subject Re: Read Latency
Date Tue, 19 Oct 2010 18:06:30 GMT
Wayne, 
I'm calling cassandra from Python and have not seen too many 3 second reads. 

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. 

DEBUG [pool-1-thread-64] 2010-10-18 19:25:28,867 StorageProxy.java (line 471) strongread reading
data for SliceFromReadCommand(table='table', key='key1', column_parent='QueryPath(columnFamilyName='fact',
superColumnName='null', columnName='null')', start='503a', finish='503a7c', reversed=false,
count=10000000) 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.
> 
> 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.
>> 
>> 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.
>> 
>> Thanks for your help.
>> 
> 
> 
> 
> -- 
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com


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