On 2 Dec 2008, at 15:55, acechase wrote:
>
> David,
>
> I don't think it would be possible to support the enumerable interface
> in this extension because it would negate the memory management
> benefits that are the reason for using such a technique. Looking at
> the code, it looks like Andreas instantiates one ruby object at a time
> from the result set, then yields that object to the block for work to
> be done on it and frees the object after the yield returns (it's a
> little fancier than this with the Oracle extension, but in the MySQL
> version that's about it). If you were to allow for things like select/
> reject, inject, etc then you're back in a situation where some
> potentially large subset (or all) of those ruby objects are going to
> be held in memory.
I don't thing that's necessarily true.
Consider for example
(1..10000000).select {|x| x == 100000}
This range contains ten million elements, but executing that statement
doesn't require having all of those in memory at any given time (keep
an eye on ruby's memory consumption while this runs)
On the other hand this would (1..10000000).to_a.select {|x| x == 100000}
Of course if the result set you are returning is large eg
(1..10000000).to_a.select {|x| x % 2 == 0 } then that will take a big
chunk of memory but that seems fair enough.
Fred
>
>
> As for named scopes, like you said, I think that just works. The named
> scopes just insert there additional magic into the final query that
> gets made (adds additional conditions, joins, etc).
>
> Cheers,
> Andrew
>
> On Dec 1, 1:47 pm, "David Masover" <[EMAIL PROTECTED]> wrote:
>> On Sat, Nov 29, 2008 at 8:14 AM, Andreas Gungl <[EMAIL PROTECTED]>
>> wrote:
>>
>>> MyTable.find_each_by_sql("some SQL here") { |my_table| ... }
>>
>>> MyTable.find_each(:all, :conditions => ...,
>>> :include => ...) { |my_table| ... }
>>
>> Any chance of having these work by scope/proxy, instead? For
>> instance:
>>
>> MyTable.all.each do |record|
>> ...
>> end
>>
>> Or, something like this, with named scopes:
>>
>> User.registered.customers.each do |user|
>> ...
>> end
>>
>> I think this already works, actually -- it just implicitly converts
>> the
>> AssociationProxy to an array. In other words, it slurps the entire
>> result
>> set. It would be nice if this behavior could be made to
>> transparently (or
>> optionally) do what you've implemented, rather than inventing a
>> whole new
>> interface -- for example, find_each doesn't help when you want to
>> use other
>> things from Enumerable, like select/reject, inject, etc.
> >
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