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From "Laing, Michael" <michael.la...@nytimes.com>
Subject Re: ALLOW FILTERING usage
Date Mon, 17 Mar 2014 11:16:54 GMT
Your second query is invalid:

*Bad Request: Partition KEY part key cannot be restricted by IN relation
(only the last part of the partition key can)*

ml


On Mon, Mar 17, 2014 at 6:56 AM, Tupshin Harper <tupshin@tupshin.com> wrote:

> It's the difference between reading from only the partitions that you are
> interested, vs reading every single partition before filtering the
> results.  At scale, and assuming you don't actually need to read every
> partition, there would be a huge difference.
>
> If the model requires you to read every partition in the table in the IN
> approach, then there probably won't be much difference.
>
> In general, I would prefer the approach where you explicitly specify the
> keys you are needing to poll.
>
> -Tupshin
> On Mar 17, 2014 6:51 AM, "Kasper Middelboe Petersen" <kasper@sybogames.com>
> wrote:
>
>> Hi,
>>
>> I have a table:
>>
>> CREATE TABLE json (
>>        key text,
>>        group text,
>>        date timestamp,
>>        json text,
>>        PRIMARY KEY((key, group), date)
>> ) WITH CLUSTERING ORDER BY (date DESC);
>>
>> This table will contain a small amount of data (only what an
>> administrator creates by hand - a year from now maybe 6 different keys,
>> 10-15 groups for a total of 60-90 rows each with up to maybe 15 columns).
>>
>> I need the application to detect changes to this and was planning to poll
>> the table every few minutes for new content (while its not often its
>> updated, the update needs to go live fairly quick).
>>
>> My question then is how big, if any, a difference there would be to doing:
>> SELECT * FROM json WHERE date < :now: AND date > :lastCheck: ALLOW
>> FILTERING
>> to
>> SELECT * FROM json WHERE key IN (<key1...key6>) AND group IN
>> (<group1...group15>) AND date < :now: AND date > :lastCheck:
>>
>>
>> /Kasper
>>
>

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