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From DuyHai Doan <doanduy...@gmail.com>
Subject Re: Cassandra 3.1 - Aggregation query failure
Date Thu, 24 Dec 2015 09:16:51 GMT
The exception stack trace at client side shows some issue with File
Permission. Try to look for the same error message in system.log to chase
down the root issue.

"Would trying the Datastax distribution offer any better chances?" --> No,
DSC is just a packaging of C* OSS

On Thu, Dec 24, 2015 at 7:07 AM, Dinesh Shanbhag <
dinesh.shanbhag@isanasystems.com> wrote:

>
> Even if aggregation that forces a full table scan across partitions is not
> recommended, the message/exception does seems unrelated to partitioning:
>
>    cqlsh:flightdata> select late_flights(uniquecarrier, depdel15) from
>    flightsbydate in ('2015-09-15', '2015-09-16',
>    '2015-09-17', '2015-09-18', '2015-09-19', '2015-09-20', '2015-09-21');
>
>    Traceback (most recent call last):
>       File "CassandraInstall-3.1/bin/cqlsh.py", line 1258, in
>    perform_simple_statement
>         result = future.result()
>       File
>
>  "/home/wpl/CassandraInstall-3.1/bin/../lib/cassandra-driver-internal-only-3.0.0-6af642d.zip/cassandra-driver-3.0.0-6af642d/cassandra/cluster.py",
>
>    line 3122, in result
>         raise self._final_exception
>    FunctionFailure: code=1400 [User Defined Function failure]
>    message="execution of 'flightdata.state_late_flights[map<text,
>    frozen<tuple<int, int>>>, text, decimal]' failed:
>    java.security.AccessControlException: access denied
>    ("java.io.FilePermission"
>    "/home/wpl/CassandraInstall-3.1/conf/logback.xml" "read")"
>
> Is that right?
>
> And note that this same aggregation query (on a subset of the month's
> days) does complete successfully sometimes.
>
> The behavior is similar with Cassandra 3.0 as well: on the same set of
> days, the query sometimes succeeds, fails most times.  Would trying the
> Datastax distribution offer any better chances?
>
> Thanks,
> Dinesh.
>
>
> On 12/24/2015 2:59 AM, DuyHai Doan wrote:
>
>> Thanks for the pointer on internal paging Tyler, I missed this one. But
>> then it raises some questions:
>>
>> 1. Is it possible to "tune" the page size or is it hard-coded internally ?
>> 2. Is read-repair performed on EACH page or is it done on the whole
>> requested rows once they are fetched ?
>>
>> Question 2. is relevant in some particular scenarios when the user is
>> using CL QUORUM (or more) and some replicas are out-of-sync. Even in the
>> case of aggregation over a single partition, if this partition is wide and
>> spans many fetch pages, the time the coordinator performs all the
>> read-repair and reconcile over QUORUM replicas, the query may timeout very
>> quickly.
>>
>>
>> On Fri, Dec 18, 2015 at 5:26 PM, Tyler Hobbs <tyler@datastax.com <mailto:
>> tyler@datastax.com>> wrote:
>>
>>
>>     On Fri, Dec 18, 2015 at 9:17 AM, DuyHai Doan <doanduyhai@gmail.com
>>     <mailto:doanduyhai@gmail.com>> wrote:
>>
>>         Cassandra will perform a full table scan and fetch all the
>>         data in memory to apply the aggregate function.
>>
>>
>>     Just to clarify for others on the list: when executing aggregation
>>     functions, Cassandra /will/ use paging internally, so at most one
>>     page worth of data will be held in memory at a time.  However, if
>>     your aggregation function retains a large amount of data, this may
>>     contribute to heap pressure.
>>
>>
>>     --     Tyler Hobbs
>>     DataStax <http://datastax.com/>
>>
>>
>>
>

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