On Thursday, June 26, 2014 6:22:01 AM UTC-7, Hiroyuki Sato wrote:
>
> Dear members.
>
> I'm newbie Sequel.
> Could you tell me best approach and example to represent Unix directory
> hierarchy with Sequel and Sqlite3?
>
> Especially, I would like to know the following
>
> How to find '/path/to/deepchild' node with small cost.
>
> It's tree, and I found rcte_tree plugin. and I wrote the following code.
>
> Alternatively, Should I uses "Nested Sets Model" for that?
>
> Sincerely.
>
> require 'sqlite3'
> require 'sequel'
> require 'pp'
>
> dbpath = File.expand_path(File.dirname(__FILE__),"tree.db")
>
> DB = Sequel.connect("sqlite://#{dbpath}")
>
>
> unless DB.table_exists?(:file_trees)
>
> # create table
> DB.create_table :file_trees do
> primary_key :id
> String :name
> Integer :uid
> Integer :gid
> # And some attributes
> Numeric :parent_id
>
Note that using Numeric here is a bad idea. This is a relationship, you
want to use foreign_key:
foreign_key :parent_id, :file_trees
> end
>
> end
>
> class FileTree < Sequel::Model
> plugin :rcte_tree, :single_root => true
> end
>
> FileTree.create(:name => "root")
> FileTree.create(:name => "child",:parent_id => FileTree.root.id)
>
> My Goal
>
> represent common file operation logging like the following.
>
> * create new node in '/path/to/deepchild'
> * list child in '/path/to/deepchild'
> * move node from '/path/to/a' to '/new/path/b'
> * remove node '/path/to/a' and child.
> * copy node '/path/to/a' to '/new/path/to/b'
>
Using rcte_tree should work. An alternative approach is just to store the
path as a column (either instead of or in addition to the name column).
With an index on the path, most directory operations should be fast,
probably faster than rcte_tree in some use cases and slower in others.
Doing this means you don't need to store a foreign key to the parent, you
just operate on the path. Not sure which way is better.
Thanks,
Jeremy
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