[web-devel] Fwd: Sql join feature in persistent

[Антон Чешков]

Of course using RDBMS directly will give the best results. Especially for
large data volumes.
But to have this feature in application layer  is convenient.

Also i am sure that solutions "a la HaskellDB" must be too.
I see this solution as separate module. Developer must have choice.


2011/2/22 Paolo Losi <paolo.losi at gmail.com>

>
>
> 2011/2/22 Антон Чешков <acheshkov at gmail.com>
>
>> I want join  its by some rule and take only first "N" results. In this
>> case i do not want serve all datasets entirely. I would like to make as
>> little as possible.
>> I think this algorithms  are exist.
>>
>
> Those algorithms exist indeed and have been implemented in last 25 years
> inside RDBMS as query optimizers.
> The question is, how much is that reasonable to re-implement in
> Haskell/Persistent?
> My 2 cent guess is that there are two viable options:
>
> 1) For Relational Backends, when scalability concerns raised by Max are not
> important,
>     the approach of a monadic DSL a la HaskellDB is the best.
>     Basically the library job is to build the SQL query and let the RDBMS
> optmizer
>     do its job.
>
> 2) For NOSQL Backends, the solution is to code your hand rolled queries as
> it can be
>     done with persistent now (the "do nothing" solution). That is the
> approach suggested
>     for redis, for example...
>
> Paolo
>
>
>
>
> --
> Paolo Losi
> e-mail: paolo at enuan.com
> mob:   +39 348 7705261
>
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-- 
Best regards,
Cheshkov Anton
Phone: +7 909 005 18 82
Phone: +7 931 511 47 37
Skype: cheshkov_anton
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