Hello Oliver,

I don't see this being a particularly good fit for Cassandra, but I hope
someone confirms this.

However, your use case did look interesting for another project I've
interacted with indirectly, Pilosa, which used to have a Cassandra backend
before a complete Golang rewrite: https://github.com/pilosa/pilosa.

It seems as though the intersect PQL command may work for your use case:



Joaquin Casares
Austin, TX

Apache Cassandra Consulting

On Fri, Jan 5, 2018 at 5:15 PM, Oliver Ruebenacker <cur...@gmail.com> wrote:

>      Hello,
>   Let's say I have a table that has one column with a unique id as a
> primary key, and then hundreds of columns of floats, although a large
> fraction of cells are empty.
>   I want to create an application that allows users to pick one or more
> number columns, specify a condition (equality or inequality) for each
> number column picked, and then get all rows that satisfy all the conditions
> provided. An empty cell would mean condition is not fulfilled.
>   (for example, find all rows for which column35 < 0.5 AND column72 > 1.5
> AND column236 < 0.1)
>   What's the best way to enable this? A secondary index for each number
> column? Would I have to obtain all columns that satisfy one condition and
> filter them down, or is there a better way? Does Cassandra support finding
> out which index best to start with?
>   Thanks!
>      Best, Oliver
> --
> Oliver Ruebenacker
> Senior Software Engineer, Diabetes Portal
> <http://www.type2diabetesgenetics.org/>, Broad Institute
> <http://www.broadinstitute.org/>

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