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From Robert Wille <rwi...@fold3.com>
Subject Re: Practical limit on number of column families
Date Mon, 29 Feb 2016 19:35:46 GMT
Yes, there is memory overhead for each column family, effectively limiting the number of column
families. The general wisdom is that you should limit yourself to a few hundred.

Robert

On Feb 29, 2016, at 10:30 AM, Fernando Jimenez <fernando.jimenez@wealth-port.com<mailto:fernando.jimenez@wealth-port.com>>
wrote:

Hi all

I have a use case for Cassandra that would require creating a large number of column families.
I have found references to early versions of Cassandra where each column family would require
a fixed amount of memory on all nodes, effectively imposing an upper limit on the total number
of CFs. I have also seen rumblings that this may have been fixed in later versions.

To put the question to rest, I have setup a DSE sandbox and created some code to generate
column families populated with 3,000 entries each.

Unfortunately I have now hit this issue: https://issues.apache.org/jira/browse/CASSANDRA-9291

So I will have to retest against Cassandra 3.0 instead

However, I would like to understand the limitations regarding creation of column families.

* Is there a practical upper limit?
* is this a fixed limit, or does it scale as more nodes are added into the cluster?
* Is there a difference between one keyspace with thousands of column families, vs thousands
of keyspaces with only a few column families each?

I haven’t found any hard evidence/documentation to help me here, but if you can point me
in the right direction, I will oblige and RTFM away.

Many thanks for your help!

Cheers
FJ




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