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From Martin von Zweigbergk <martin.von.zweigbe...@gmail.com>
Subject Re: CQL: No indexed column error when < or <= in WHERE clause
Date Sun, 14 Aug 2011 13:11:28 GMT
Hi Jens,

I have never used CQL myself and I have barely used Cassandra, but I
think I've seen it mentioned before on this list that you need to use
compare for equality on at least one column (as indicated by "No
indexed columns present in by-columns clause with "equals" operator").
The lookup will then be done based on that column and additional
filtering (such as for "less than") will be done on the result of the
first lookup, which can potentially be a large data set. You might
also want to redesign your data model to allow for a more efficient
lookup.

Hope that helps (despite my lack of knowledge on the subject)
Martin

On Sun, Aug 14, 2011 at 8:53 AM, Jens Hartung <honis@gmx.de> wrote:
> I had indexed the number column in station column family. Do I also have to index another
column?
>
> What I'm wondering, when I type "get station where number = 8210;" all works fine, but
when I type "get station where number < 8210;" I'll get mentioned exception.
>
> Is there something, that I misunderstand?
>
> -------- Original-Nachricht --------
>> Datum: Sat, 13 Aug 2011 18:14:05 -0700
>> Von: Jonathan Ellis <jbellis@gmail.com>
>> An: user@cassandra.apache.org
>> Betreff: Re: CQL: No indexed column error when < or <= in WHERE clause
>
>> This is covered in
>> http://www.datastax.com/dev/blog/whats-new-cassandra-07-secondary-indexes
>>
>> On Sat, Aug 13, 2011 at 2:49 PM, Jens Hartung <honis@gmx.de> wrote:
>> > Hi together,
>> >
>> > first, I'm using Cassandra Version 0.8.4 and access it via CQL 1.0.3.
>> >
>> > When I select data from Cassandra with = in WHERE clause, everything
>> works fine, but when using <= or < in WHERE clause, I always get following
>> Exception:
>> >
>> > java.sql.SQLException: No indexed columns present in by-columns clause
>> with "equals" operator
>> >        at
>> org.apache.cassandra.cql.jdbc.CassandraStatement.executeQuery(CassandraStatement.java:242)
>> >        at
>> columnfamily.queries.CassandraQueries.singleColumnSelect(CassandraQueries.java:147)
>> > ...
>> >
>> > My select-statement: "SELECT number FROM station WHERE number <= 8210;"
>> >
>> > Output of describe keyspace (within cli):
>> > ColumnFamily: station
>> >      Key Validation Class: org.apache.cassandra.db.marshal.UTF8Type
>> >      Default column value validator:
>> org.apache.cassandra.db.marshal.UTF8Type
>> >      Columns sorted by: org.apache.cassandra.db.marshal.UTF8Type
>> >      Row cache size / save period in seconds: 0.0/0
>> >      Key cache size / save period in seconds: 200000.0/14400
>> >      Memtable thresholds: 0.2109375/1440/45 (millions of
>> ops/minutes/MB)
>> >      GC grace seconds: 864000
>> >      Compaction min/max thresholds: 4/32
>> >      Read repair chance: 1.0
>> >      Replicate on write: true
>> >      Built indexes: [station.station_number_idx]
>> >      Column Metadata:
>> >        [...]
>> >        Column Name: number
>> >          Validation Class: org.apache.cassandra.db.marshal.LongType
>> >          Index Name: station_number_idx
>> >          Index Type: KEYS
>> >        [...]
>> >
>> > Are the <, <=, >=, > operators not supported at this time?
>> >
>> > Greetings
>> > Jens
>> > --
>> > NEU: FreePhone - 0ct/min Handyspartarif mit Geld-zurück-Garantie!
>> > Jetzt informieren: http://www.gmx.net/de/go/freephone
>> >
>>
>>
>>
>> --
>> Jonathan Ellis
>> Project Chair, Apache Cassandra
>> co-founder of DataStax, the source for professional Cassandra support
>> http://www.datastax.com
>
> --
> NEU: FreePhone - 0ct/min Handyspartarif mit Geld-zurück-Garantie!
> Jetzt informieren: http://www.gmx.net/de/go/freephone
>

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