SST Tables Per read in cfhistorgrams

[Anishek Agarwal <an...@gmail.com>]

Hello,

I am seeing that even though the bloom filter fp ratio being set to 0.1 the
actual is at about .55 and on looking at the histograms of the table i see
that there are reads going to 3+ SSTtables even though the way i am
querying for read it should look at the most recent row only since i have
time as part of my partition_key. I have a composite partition key with
((long,timestamp)).

Question: The Number of SST tables read, would it also include those where
the bloom filter gave a false positive ? or is it just the number to
actually do the reads.

Thanks
Anishek

Re: SST Tables Per read in cfhistorgrams

[Robert Coli <rc...@eventbrite.com>]

On Sun, May 17, 2015 at 9:59 PM, Anishek Agarwal <an...@gmail.com> wrote:

> Question: The Number of SST tables read, would it also include those where
> the bloom filter gave a false positive ? or is it just the number to
> actually do the reads.
>

It doesn't know the positive is false until it reads into the SSTable. The
purpose of the bloom filter is to avoid this read, if possible.

=Rob