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 <paulinga...@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
>
>
>
