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From aaron morton <aa...@thelastpickle.com>
Subject Re: Using map<varchar, varchar> type with composite primary key causes significant performance decrease
Date Thu, 18 Apr 2013 18:37:14 GMT
> After about 1-2K inserts I get significant performance decrease.
A decrease in performance doing what ? 

Cheers

-----------------
Aaron Morton
Freelance Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 19/04/2013, at 4:43 AM, Oleksandr Petrov <oleksandr.petrov@gmail.com> wrote:

> Hi,
> 
> I'm trying to persist some event data, I've tried to identify the bottleneck, and it
seems to work like that:
> 
> If I create a table with primary key based on (application, environment, type and emitted_at):
> 
> CREATE TABLE events (application varchar, environment varchar, type varchar, additional_info
map<varchar, varchar>, hostname varchar, emitted_at timestamp, 
> PRIMARY KEY (application, environment, type, emitted_at));
> 
> And insert events via CQL, prepared statements:
> 
> INSERT INTO events (environment, application, hostname, emitted_at, type, additional_info)
VALUES (?, ?, ?, ?, ?, ?);
> 
> Values are: "local" "analytics" "noname" #inst "2013-04-18T16:37:02.723-00:00" "event_type"
{"some" "value"}
> 
> After about 1-2K inserts I get significant performance decrease.
> 
> I've tried using only emitted_at (timestamp) as a primary key, OR writing additional_info
data as a serialized JSON (varchar) instead of Map. Both scenarios seem to solve the performance
degradation.
> 
> I'm using Cassandra 1.2.3 from DataStax repository, running it on 2-core machine with
2GB Ram.
> 
> What could I do wrong here? What may cause performance issues?.. 
> Thank you
> 
> 
> -- 
> alex p


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