It uses the index...
cqlsh:dev> tracing on;
Now tracing requests.
cqlsh:dev>
cqlsh:dev>
cqlsh:dev> SELECT id, flag from foo WHERE TOKEN(id) > '-9939393' AND TOKEN(id)
<= '0' AND flag=true;
Tracing session: 128cab90-6982-11e2-8cd1-51eaa232562e
activity | timestamp | source
| source_elapsed
----------------------------------------------------+--------------+-----------+----------------
execute_cql3_query | 08:36:55,244 | 127.0.0.1
| 0
Parsing statement | 08:36:55,244 | 127.0.0.1
| 600
Peparing statement | 08:36:55,245 | 127.0.0.1
| 1408
Determining replicas to query | 08:36:55,246 | 127.0.0.1
| 1924
Executing indexed scan for (max(-9939393), max(0)] | 08:36:55,247 | 127.0.0.1
| 2956
Executing single-partition query on foo.flag_index | 08:36:55,247 | 127.0.0.1
| 3192
Acquiring sstable references | 08:36:55,247 | 127.0.0.1
| 3220
Merging memtable contents | 08:36:55,247 | 127.0.0.1
| 3265
Scanned 0 rows and matched 0 | 08:36:55,247 | 127.0.0.1
| 3396
Request complete | 08:36:55,247 | 127.0.0.1
| 3644
It reads from the secondary index and discards keys that are outside of the
token range.
Cheers
-----------------
Aaron Morton
Freelance Cassandra Developer
New Zealand
@aaronmorton
http://www.thelastpickle.com
On 28/01/2013, at 4:24 PM, Mike Sample <mike.sam...@gmail.com> wrote:
> Does the following FAQ entry hold even when the partion key is also
> constrained in the query (by token())?
>
> http://wiki.apache.org/cassandra/SecondaryIndexes:
> ==
> Q: How does choice of Consistency Level affect cluster availability when
> using secondary indexes?
>
> A: Because secondary indexes are distributed, you must have CL nodes
> available for all token ranges in the cluster in order to complete a query.
> For example, with RF = 3, when two out of three consecutive nodes in the ring
> are unavailable, all secondary index queries at CL = QUORUM will fail,
> however secondary index queries at CL = ONE will succeed. This is true
> regardless of cluster size."
> ==
>
> For example:
>
> CREATE TABLE foo (
> id uuid,
> seq_num bigint,
> flag boolean,
> some_other_data blob,
> PRIMARY KEY (id,seq_num)
> );
>
> CREATE INDEX flag_index ON foo (flag);
>
> SELECT id, flag from foo WHERE TOKEN(id) > '-9939393' AND TOKEN(id) <= '0'
> AND flag=true;
>
> Would the above query with LOCAL_QUORUM succeed given the following? IE is
> the token range used first trim node selection?
>
> * the cluster has 18 nodes
> * foo is in a keyspace with a replication factor of 3 for that data center
> * 2 nodes in one of the replication groups are down
> * the token range in the query is not in the range of the down nodes
>
>
> Thanks in advance!
