Cassandra partitions data across the cluster based on PK, thus is optimized for WHERE PK=...
You are doing table scans, the opposite of what a distributed system is designed for. However, some users find Solr helps with queries like yours. To learn what C* is good at, read this: http://planetcassandra.org/blog/getting-started-with-time-series-data-modeling/ Thanks, James Briggs. -- Cassandra/MySQL DBA. Available in San Jose area or remote. cass_top: https://github.com/jamesbriggs/cassandra-top ________________________________ From: Check Peck <comptechge...@gmail.com> To: user <user@cassandra.apache.org> Sent: Wednesday, September 17, 2014 3:35 PM Subject: Re: Cassandra Data Model design It takes around more than 50 seconds to return back 500 records from cqlsh command not from the code so that's why I am saying it is pretty slow. On Wed, Sep 17, 2014 at 3:17 PM, Hao Cheng <br...@critica.io> wrote: How slow is slow? Regardless of the data model question, in my experience 500 rows of relatively light content should be lightning fast. Looking at my performance results on a test cluster of 3x r3.large AWS instances, we reach an op rate on Cassandra's stress test of at least 1000 operations per second and on average 7500 operations for second over the stress test data set. > > >More broadly, it seems like you would benefit from either deltas (only >retrieve new data) or something like paging (only retrieve currently relevant >data), although its really difficult to say without more information. > > >On Wed, Sep 17, 2014 at 1:01 PM, Check Peck <comptechge...@gmail.com> wrote: > >I have recently started working with Cassandra. We have cassandra cluster >which is using DSE 4.0 version and has VNODES enabled. We have a tables like >this - >> >>Below is my first table - >> >> CREATE TABLE customers ( >> customer_id int PRIMARY KEY, >> last_modified_date timeuuid, >> customer_value text >> ) >> >>Read query pattern is like this on above table as of now since we need to get >>everything from above table and load it into our application memory every x >>minutes. >> >> select customer_id, customer_value from datakeyspace.customers; >> >>We have second table like this - >> >> CREATE TABLE client_data ( >> client_name text PRIMARY KEY, >> client_id text, >> creation_date timestamp, >> is_valid int, >> last_modified_date timestamp >> ) >> >>Right now in the above table, we have 500 records and all those records has >>"is_valid" column value set as 1. And the read query pattern is like this on >>above table as of now since we need to get everything from above table and >>load it into our application memory every x minutes so the below query will >>return me all 500 records since everything has is_valid set to 1. >> >> select client_name, client_id from datakeyspace.client_data where >> is_valid=1; >> >>Since our cluster is VNODES enabled so my above query pattern is not >>efficient at all and it is taking lot of time to get the data from Cassandra. >>We are reading from these table with consistency level QUORUM. >> >>Is there any possibility of improving our data model? >> >>Any suggestions will be greatly appreciated. >> >
