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From James Golick <jamesgol...@gmail.com>
Subject Re: Reading thousands of columns
Date Wed, 14 Apr 2010 20:19:49 GMT
The values are empty. It's 3000 UUIDs.

On Wed, Apr 14, 2010 at 12:40 PM, Avinash Lakshman <
avinash.lakshman@gmail.com> wrote:

> How large are the values? How much data on disk?
>
> On Wednesday, April 14, 2010, James Golick <jamesgolick@gmail.com> wrote:
> > 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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