On 19 Dec 2008, at 01:25, Greg Hauptmann wrote:
> Hi,
>
> How complex a query can ActiveRecord handle before it's better using
> Raw SQL or a View???
>
Depends what you mean by handle. If you mean "will ruby run out of
steam" then that's purely a function of the result set, instantiating
1 million ActiveRecord objects is probably not a good idea.
If you mean handle as in get ActiveRecord to generate it without
writing any sql yourself then I don't believe there's a hard and fast
rule or anything like that.
You might be able to get away with
Transaction.find :all, :joins => [:category, {:allocation => :person}],
:conditions => {'people.id' => bob, 'categories.tax_id'
=>
1234, 'transactions.created_at' => (1.week.ago .. Time.now)}
or maybe the relations you need to express don't quite map to those
things activerecord makes easy. It's a case by case thing, much as I'd
far write the above than write the equivalent sql, I wouldn't waste
time trying to force activerecord through hoops when it was clear that
it wasn't time well spent.
Fred
> I need to calculate for example taxable income via a query going
> across 5 tables. Some like this: Find all transaction records
> (transactions table), for which they are allocated (via allocation
> table) to person X (person table), for transaction dates within
> date1 & date2, for which the category (categories table) associated
> with transaction, has a tax_id (from tax_codes table) of XYZ. I
> will need to reuse this type of query as I build a report of various
> tax categories.
>
> Question - What would Rails best practice way for the above?
>
> [I'm thinking best to create a flat view of this and use this to
> then query against]
>
> Thanks
>
> >
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