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From Paul van Hoven <paul.van.ho...@googlemail.com>
Subject Re: CQL : Request did not complete within rpc_timeout
Date Sun, 03 Feb 2013 15:56:51 GMT
Okay, here is the schema (actually it is in german, but I translated
the column names such that it is easier to read for an international
audience):

cqlsh:demodb> describe table offerten_log_archiv;

CREATE TABLE offerten_log_archiv (
  offerte_id int PRIMARY KEY,
  aktionen int,
  angezeigt bigint,
  datum timestamp,
  gutschrift bigint,
  kampagne_id int,
  klicks int,
  klicks_ungueltig int,
  kosten bigint,
  statistik_id bigint,
  stunden int,
  werbeflaeche_id int,
  werbemittel_id int
) WITH
  bloom_filter_fp_chance=0.010000 AND
  caching='KEYS_ONLY' AND
  comment='' AND
  dclocal_read_repair_chance=0.000000 AND
  gc_grace_seconds=864000 AND
  read_repair_chance=0.100000 AND
  replicate_on_write='true' AND
  compaction={'class': 'SizeTieredCompactionStrategy'};

CREATE INDEX datum_key ON offerten_log_archiv (datum);

CREATE INDEX stunden_key ON offerten_log_archiv (stunden);

cqlsh:demodb>

This is the query I'm trying to perform:
cqlsh:demodb> select * from ola where date > '2013-01-01' and hour = 0
limit 10 allow filtering;
Request did not complete within rpc_timeout.

ola = offerten_log_archiv (table name)
hour = stunde (column name)
date = datum (column name)

I hope this information makes my problem more clear.



2013/2/3 Edward Capriolo <edlinuxguru@gmail.com>:
> Without seeing your schema it is hard to say, but in some cases "ALLOW
> FILTERING" might be considered "EXPECT THIS COULD BE SLOW". It could
> mean the query is not hitting and index and is going to page through
> large amounts of data.
>
> On Sun, Feb 3, 2013 at 9:42 AM, Paul van Hoven
> <paul.van.hoven@googlemail.com> wrote:
>> After figuring out how to use the ">" operator on an secondary index I
>> noticed that in a column family of about 5.5 million datasets I get a
>> rpc_timeout when trying to read data from this table. In the concrete
>> situation I want to request data younger than January 1 2013. The
>> number of rows that should be affected are about 1 million. When doing
>> the request I get a timeout error:
>>
>> cqlsh:demodb> select * from ola where date > '2013-01-01' and hour = 0
>> limit 10 allow filtering;
>> Request did not complete within rpc_timeout.
>>
>> Actually I find this very confusing since I would except an
>> exceptional performance gain in comparison to a similar sql query.
>> Therefore, I think the query I'm performing is not appropriate for
>> cassandra, although I would do a query like that in this manner on a
>> sql database. So my question now is: How should I perfrom this query
>> on cassandra?

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