incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Kevin Burton <bur...@spinn3r.com>
Subject Re: Fetching ONE cell with a row cache hit takes 1 second on an idle box?
Date Wed, 02 Jul 2014 01:06:11 GMT
you know.. one thing I failed to mention.. .is that this is going into a
"bucket" and while it's a logical row, the physical row is like 500MB …
according to compaction logs.

is the ENTIRE physical row going into the cache as one unit?  That's
definitely going to be a problem in this model.  500MB is a big atomic unit.

also.. I assume it's having to do a binary search within the physical row ?


On Tue, Jul 1, 2014 at 5:54 PM, Kevin Burton <burton@spinn3r.com> wrote:

> I'm really perplexed on this one..  I think this must be a bug or some
> misconfiguration somewhere.
>
> I'm fetching ONE row which is one cell in my table.
>
> The row is in the row cache, sitting in memory.
>
> SELECT sequence from content where bucket=98 AND sequence =
> 1403481494000005742;
>
> And look at the trace below… it's taking 1000ms to go to the row cache?
>  That seems insane!
>
> Something must be broken somewhere.. Any advice in what I should be
> looking into?
>
> The VM has plenty of memory so I don't think it's GC.
>
>  activity
>                             | timestamp    | source      | source_elapsed
>
> ------------------------------------------------------------------------------------------------------+--------------+-------------+----------------
>
>          execute_cql3_query | 19:48:48,559 | 10.24.23.94 |              0
>  Parsing SELECT sequence from content where bucket=98 AND sequence =
> 1403481494000005742 LIMIT 10000; | 19:48:48,559 | 10.24.23.94 |
> 63
>
>         Preparing statement | 19:48:48,559 | 10.24.23.94 |            153
>
>               Row cache hit | 19:48:49,706 | 10.24.23.94 |        1147108
>                                                                    Read 1
> live and 0 tombstoned cells | 19:48:49,706 | 10.24.23.94 |        1147236
>
>            Request complete | 19:48:49,706 | 10.24.23.94 |        1147412
>
>
> --
>
> Founder/CEO Spinn3r.com
> Location: *San Francisco, CA*
> blog: http://burtonator.wordpress.com
>  … or check out my Google+ profile
> <https://plus.google.com/102718274791889610666/posts>
> <http://spinn3r.com>
>
>


-- 

Founder/CEO Spinn3r.com
Location: *San Francisco, CA*
blog: http://burtonator.wordpress.com
… or check out my Google+ profile
<https://plus.google.com/102718274791889610666/posts>
<http://spinn3r.com>

Mime
View raw message