[Rails] find_by* efficiency - blocks?

[Ara.T.Howard]

On Fri, 25 Feb 2005, hadley wickham wrote:

>> no.  here is an example using sqlite:
>>
>> this technique uses sqlite's ability to pass a block with which to handle each
>> tuple as it is returned from the db.
>>
>>    jib:~ > cat a.rb
>>    #!/usr/bin/env ruby
>>    require 'sqlite'
>>    db = SQLite::Database::new(ARGV.shift, 0)
>>    db.use_array = true
>>    db.execute('select * from jobs'){|tuple| p tuple}
>>
>>    jib:~ > time a.rb db > /dev/null
>>
>>    real    0m1.510s
>>    user    0m1.420s
>>    sys     0m0.080s
>
> Aaaaah.  Now I see - I was actually doing something similar (dumping
> 30,000 records into a CSV file) a couple of days ago and thought there
> must be a better way than loading them all into memory at once (and
> this obviously that better way).

the csv module that comes with ruby supports iterator type usage both for
reading and writing - i was just using it today ;-)

> Thanks for the detailed explanation and please do look into adding this
> functionality to rails!

it would be very, very easy to do - only bariers would be time and ability to
test things like DB2, which i do not have access to.

cheers.

-a
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