Re: migration

Frederick Cheung
Fri, 03 Oct 2008 16:00:22 -0000

On 3 Oct 2008, at 16:46, Ajit wrote:

>
> hello All
>
> I am trying to create a table using rails migrations. after creating
> the table i want to move data from one table to newly created table.
> everything seems to be working fine.. only issue is speed of moving
> data.
>
> Abc.find(:all).each do |a|
>
>      xyz.new do |x|
>              xyz.id = a.id
>             xyz.save
>      end
> end
>
> i have over 200,000 rows in my table.. and it is very slow...
>
Ouch. I would probably drop down to some raw sql (good old insert into
x values(...) (select ... from))
It might be slightly quicker if you :
- didn''t load all the the abcs in one go
- did each chunk of abcs in a transaction (cuts down on how often the
database has to flush to disk)

Fred
> is there a better way to move data quickly?
>
> Please advice..
>
> Cheers
>
> Ajit
>
>
> >


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