Rails - Apr 2006 - ActiveRecord: Exclude some columns while fetching

I have models with large TEXT, BLOB columns and I don''t wanna fetch
them
everytime. Is it possible to omit columns when fetching records from DB?
Sorry, if it''s trivial, but I can''t find helpful information
in docs.

Two alternatives:

1) Define a View, not displaying your blobs.
2) Use find_by_sql. Mention the columns you need.

Christer

zven wrote:
> I have models with large TEXT, BLOB columns and I don''t wanna
fetch them
> everytime. Is it possible to omit columns when fetching records from DB?
> Sorry, if it''s trivial, but I can''t find helpful
information in docs.

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Posted via http://www.ruby-forum.com/.

Third alternative: create a new table that just holds the blob data.  
Then make this table a has_one association off the table that you do  
all the searching in. Basically, you keep the main table for all the  
meta data related to the blobs (which you''re always doing finds on)  
and only when you need to display the full details of one of those  
records do you then build the find with a :include to the has_one table.

It''s a little more bookkeeping in your controllers, but it''s a
technique I''ve used several times and it works really well. I also  
think it''s one of the more Rails-like solutions to this kind of  
problem. One thing to keep in mind, if you haven''t noticed that your  
finds on this model are coming back a little slower than you would  
like, using any of these solutions would be "premature optimization",
which goes against normal Agile Developement practices. Basically, if  
the database has no trouble giving you the TEXT and BLOB fields on  
every find request, why should you care...

-Brian

On Apr 23, 2006, at 05:32 AM, Christer Nilsson wrote:
> Two alternatives:
>
> 1) Define a View, not displaying your blobs.
> 2) Use find_by_sql. Mention the columns you need.
>
> Christer
>
> zven wrote:
>> I have models with large TEXT, BLOB columns and I don''t wanna
>> fetch them
>> everytime. Is it possible to omit columns when fetching records  
>> from DB?
>> Sorry, if it''s trivial, but I can''t find helpful
information in docs.

You can use :select option in find method like this:
Model.find :all, :select => "id, name"

On 4/23/06, Brian V Hughes <brianvh@alum.dartmouth.org>
wrote:
>
> Third alternative: create a new table that just holds the blob data.
> Then make this table a has_one association off the table that you do
> all the searching in. Basically, you keep the main table for all the
> meta data related to the blobs (which you''re always doing finds
on)
> and only when you need to display the full details of one of those
> records do you then build the find with a :include to the has_one table.
>
> It''s a little more bookkeeping in your controllers, but
it''s a
> technique I''ve used several times and it works really well. I also
> think it''s one of the more Rails-like solutions to this kind of
> problem. One thing to keep in mind, if you haven''t noticed that
your
> finds on this model are coming back a little slower than you would
> like, using any of these solutions would be "premature
optimization",
> which goes against normal Agile Developement practices. Basically, if
> the database has no trouble giving you the TEXT and BLOB fields on
> every find request, why should you care...
>
> -Brian
>
> On Apr 23, 2006, at 05:32 AM, Christer Nilsson wrote:
> > Two alternatives:
> >
> > 1) Define a View, not displaying your blobs.
> > 2) Use find_by_sql. Mention the columns you need.
> >
> > Christer
> >
> > zven wrote:
> >> I have models with large TEXT, BLOB columns and I don''t
wanna
> >> fetch them
> >> everytime. Is it possible to omit columns when fetching records
> >> from DB?
> >> Sorry, if it''s trivial, but I can''t find helpful
information in docs.
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Bruno Celeste wrote:
> You can use :select option in find method like this:
> Model.find :all, :select => "id, name"
This is the right answer, find_by_sql is way overkill for this.

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