Clint
One approach would be to create a copy of this table and switch the
clustering columns around so version precedes family. This way you
could easily grab the 1st, 2nd, N version rows. Would this help you
in your situation?
Jonathan
> On Feb 25, 2014, at 7:49 PM, Clint Kelly <clint.ke...@gmail.com> wrote:
>
> Hi everyone,
>
> Let's say that I have a table that looks like the following:
>
> CREATE TABLE time_series_stuff (
> key text,
> family text,
> version int,
> val text,
> PRIMARY KEY (key, family, version)
> ) WITH CLUSTERING ORDER BY (family ASC, version DESC) AND
> 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
> index_interval=128 AND
> read_repair_chance=0.100000 AND
> replicate_on_write='true' AND
> populate_io_cache_on_flush='false' AND
> default_time_to_live=0 AND
> speculative_retry='99.0PERCENTILE' AND
> memtable_flush_period_in_ms=0 AND
> compaction={'class': 'SizeTieredCompactionStrategy'} AND
> compression={'sstable_compression': 'LZ4Compressor'};
>
> cqlsh:fiddle> select * from time_series_stuff ;
>
> key | family | version | val
> --------+---------+---------+--------
> monday | revenue | 3 | $$$$$$
> monday | revenue | 2 | $$$
> monday | revenue | 1 | $$
> monday | revenue | 0 | $
> monday | traffic | 2 | medium
> monday | traffic | 1 | light
> monday | traffic | 0 | heavy
>
> (7 rows)
>
> Now let's say that I'd like to perform a query that gets me the most recent N
> versions of "revenue" and "traffic."
>
> Is there a CQL query to do this? Let's say that N=1. Then I know that I can
> do:
>
> cqlsh:fiddle> select * from time_series_stuff where key='monday' and
> family='revenue' limit 1;
>
> key | family | version | val
> --------+---------+---------+--------
> monday | revenue | 3 | $$$$$$
>
> (1 rows)
>
> cqlsh:fiddle> select * from time_series_stuff where key='monday' and
> family='traffic' limit 1;
>
> key | family | version | val
> --------+---------+---------+--------
> monday | traffic | 2 | medium
>
> (1 rows)
>
> But what if I have lots of "families" and I want to get the most recent N
> versions of all of them in a single CQL statement. Is that possible?
> Unfortunately I am working on something where the family names and the number
> of most-recent versions are not known a priori (I am porting some code that
> was designed for HBase).
>
> Best regards,
> Clint
