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From Paul Ingalls <paulinga...@gmail.com>
Subject Re: Timeout reading row from CF with collections
Date Fri, 12 Jul 2013 20:14:53 GMT
Yep, that was it.  I built from the cassandra 1.2 branch and no more timeouts.  Thanks for
getting that fix into 1.2!!!!!

Paul

On Jul 12, 2013, at 1:20 AM, Sylvain Lebresne <sylvain@datastax.com> wrote:

> My bet is that you're hitting https://issues.apache.org/jira/browse/CASSANDRA-5677.
> 
> --
> Sylvain
> 
> 
> On Fri, Jul 12, 2013 at 8:17 AM, Paul Ingalls <paulingalls@gmail.com> wrote:
> I'm running into a problem trying to read data from a column family that includes a number
of collections.  
> 
> Cluster details:
> 4 nodes running 1.2.6 on VMs with 4 cpus and 7 Gb of ram.
> raid 0 striped across 4 disks for the data and logs
> each node has about 500 MB of data currently loaded
> 
> Here is the schema:
> 
> create table user_scores
> (
> 	user_id varchar,
> 	post_type varchar,
> 	score double,
> 	team_to_score_map map<varchar, double>,
> 	affiliation_to_score_map map<varchar, double>,
> 	campaign_to_score_map map<varchar, double>,
> 	person_to_score_map map<varchar, double>,
> 	primary key(user_id, post_type)
> )
> with compaction =
> {
>   'class' : 'LeveledCompactionStrategy',
>   'sstable_size_in_mb' : 10
> };
> 
> I used the leveled compaction strategy as I thought it would help with read latency…
> 
> Here is a trace of a simple select against the cluster when it had nothing else was reading
or writing (cpu was < 2%):
> 
>  activity                                                                | timestamp
   | source         | source_elapsed
> -------------------------------------------------------------------------+--------------+----------------+----------------
>                                                       execute_cql3_query | 05:51:34,557
|  100.69.176.51 |              0
>                                     Message received from /100.69.176.51 | 05:51:34,195
| 100.69.184.134 |            102
>                          Executing single-partition query on user_scores | 05:51:34,199
| 100.69.184.134 |           3512
>                                             Acquiring sstable references | 05:51:34,199
| 100.69.184.134 |           3741
>                                              Merging memtable tombstones | 05:51:34,199
| 100.69.184.134 |           3890
>                                              Key cache hit for sstable 5 | 05:51:34,199
| 100.69.184.134 |           4040
>                              Seeking to partition beginning in data file | 05:51:34,199
| 100.69.184.134 |           4059
>                               Merging data from memtables and 1 sstables | 05:51:34,200
| 100.69.184.134 |           4412
>  Parsing select * from user_scores where user_id='26257166' LIMIT 10000; | 05:51:34,558
|  100.69.176.51 |             91
>                                                       Peparing statement | 05:51:34,558
|  100.69.176.51 |            238
>                                Enqueuing data request to /100.69.184.134 | 05:51:34,558
|  100.69.176.51 |            567
>                                       Sending message to /100.69.184.134 | 05:51:34,558
|  100.69.176.51 |            979
>                                                         Request complete | 05:51:54,562
|  100.69.176.51 |       20005209
> 
> You can see that I increased the timeout and it still fails.  This seems to happen with
rows that have maps with a larger number of entries.  It is very reproducible with my current
data set.
> 
> Any ideas on why I can't query for a row?
> 
> Thanks!
> 
> Paul
> 
> 
> 


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