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From James Golick <jamesgol...@gmail.com>
Subject Re: Reading thousands of columns
Date Wed, 14 Apr 2010 19:24:10 GMT
Just for the record, I am able to repeat this locally.

I'm seeing around 150ms to read 1000 columns from a row that has 3000 in it.
If I enable the rowcache, that goes down to about 90ms. According to my
profile, 90% of the time is being spent waiting for cassandra to respond, so
it's not thrift.

On Wed, Apr 14, 2010 at 11:01 AM, Paul Prescod <prescod@gmail.com> wrote:

> On Wed, Apr 14, 2010 at 10:31 AM, Mike Malone <mike@simplegeo.com> wrote:
> > ...
> >
> > Couldn't you cache a list of keys that were returned for the key range,
> then
> > cache individual rows separately or not at all?
> > By "blowing away rows queried by key" I'm guessing you mean "pushing them
> > out of the LRU cache," not explicitly blowing them away? Either way I'm
> not
> > entirely convinced. In my experience I've had pretty good success caching
> > items that were pulled out via more complicated join / range type
> queries.
> > If your system is doing lots of range quereis, and not a lot of lookups
> by
> > key, you'd obviously see a performance win from caching the range
> queries.
> > Maybe range scan caching could be turned on separately?
>
> I agree with you that the caches should be separate, if you're going
> to cache ranges. You could imagine a single query (perhaps entered
> interactively) would replace the entire row caching all of the data
> for the systems' interactive users. For example, a summary page of who
> is most over the last month active could replace the profile
> information for the actual users who are using the system at that
> moment.
>
>  Paul Prescod
>

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