Betternestedset talk - Jan 2007 - item.level store in db

Hi List,

how do you think about storing the level of an entry into the database.

For each entry you request item.level there now is a count * request to the
database. In a huge set this can be a performance issue.

At most applications you have much more reading then writing to a database, so
this can improve performance.

For backward compatibility this could be added via an option like

class MyModel < ActiveRecord::Base
  acts_as_nested_set :level => :depth
end

Something similar it''s in acts_as_threaded or as a callback:

  def before_create
    # Update the child object with its parents attrs
    unless self[:parent_id].to_i.zero?
      self[:depth] = parent[:depth].to_i + 1
    end
  end

How do you think about this?

Cheers,

Matze

Hi Matthias,

Le 6 janv. 07, ? 12:45, Matthias Heigl a ?crit :
> how do you think about storing the level of an entry into the database.
>
> For each entry you request item.level there now is a count * request 
> to the database. In a huge set this can be a performance issue.
>
> At most applications you have much more reading then writing to a 
> database, so this can improve performance.
> ...
> How do you think about this?
Are you sure it''s not premature optimisation ? If you have benchmarks 
proving this is a weak point in betternestedset performances and your 
solution enhances them, I agree, go ahead. I would tend to think that 
db engine internal optimization can be quite as good as the one we can 
add in interpreted ruby layer...

Jean-Christophe Michel
--
symetrie.com

Better Nested Set for rails:
http://opensource.symetrie.com/trac/better_nested_set