Re: ActiveRecord: ar-each_model

Robert Walker
Wed, 11 Jan 2012 20:13:02 -0000

tvw wrote in post #1040336:
> today I went into a problem, when I had to iterate over a big result
> set. ActiveRecord produces a huge array of model instances, which
> consumed 1GB of memory on my machine. A comparable perl DBI script
> only used some KB for iterating over the result set.

It is well known that ActiveRecord objects are pretty heavy weight. My
guess is that your Perl script is instead returning you something very
light weight. Something that is little more than key value pairs for
each database row.

I''m also assuming that whatever you''re doing with this large
result set
probably doesn''t require "smart" heavy weight model objects.

In the past I used a framework that had a similar issue. It, however,
had a built-in mechanism for dealing with the issue. It had something
called "raw row fetching." Rather than returning true model objects,
with all the intelligence built into them, you could opt to fetch raw
rows that were represented by an array of dictionaries (hashes). A raw
row could then be transformed into a full fledged model object on
demand.

I don''t know if ActiveRecord provides anything similar to this
out-of-the-box. But, I''m sure someone must have developed something
like
this for Rails.

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