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From Renato Bacelar da Silveira <>
Subject Cassandra Reads a little slow - 900 keys takes 4 seconds.
Date Wed, 31 Aug 2011 09:13:30 GMT
Hi All

I am running a query against a node with about 50 Column Families.

At present One of the column families has 2,502,000 rows, each row
contains 100 columns.

I am searching for 3 columns specifically, and am doing so with Thrift's
multiget_slice(). I prepare a statement with about 900 row  keys, each
searching for a slice of 3 specific columns.

My average time taken to return from the multiget_slice() is about 4
seconds. I performed a comparative query in mysql, and the results
were returned to me in 0.75 seconds or avarage.

Is 4 seconds way too much time for Cassandra? I am sure this could
be under 1 second, like MySql.

I have resized the Thrift transport size to just 1MB so to not encounter
any timeouts, as noted if you push too many queries through. Is this
a correct assumption?

So is it too much to push 900 keys in a multiget_slice() at once? I read
that it does a concurrent fetch. I can understand threads racing for
cycles, causing waits, but somehow I think I am wrong somewhere.

Regards to ALL!

Renato da Silveira
Senior Developer


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