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From Tyler Hobbs <>
Subject Re: clarification on 100k tombstone limit in indexes
Date Wed, 13 Aug 2014 15:48:26 GMT
On Wed, Aug 13, 2014 at 4:35 AM, DuyHai Doan <> wrote:

> "add an additional integer column to the partition key (making it a
> composite partition key if it isn't already).  When inserting, randomly
> pick a value between, say, 0 and 10 to use for this column"  --> Due to the
> low cardinality of bucket (only 10), there is no guarantee that the
> partitions would be distributed evenly. But it's better than nothing.

It's important to think about it probablistically, i.e. "what is the
probability that all ten partitions belong to the same node?"  If you have
a ten node cluster (assume RF=1 for simplicity), there's a 1/10^9 (one in a
billion) chance that a single node is the owner for all partitions.  So
it's quite a bit better than nothing.  If you want to improve your odds,
bump the number up.  But, keep in mind that it's a balance, because reads
become more expensive.

> "Alternatively, instead of using a random number, you could hash the
> other key components and use the lowest bits for the value.  This has the
> advantage of being deterministic" --> Does it work with VNodes, where
> tokens are split in 256 ranges and shuffled in all nodes ?

Yes, it works perfectly fine with vnodes.

Tyler Hobbs
DataStax <>

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