Rubyisms - MySQL-dump - The Diigo Meta page

• 17 Aug 10
  

  Éric D.
• 23 Jul 10
  

  Darren Jensen

  ":select => [ fieldlist "

  rails sql tips database mysql

• 04 May 09
  

  Rodrigo de Oliveira

  This article is about Ruby On Rails and its interaction with MySQL in general.

  banco_de_dados mysql programação rails ruby sql from_delicious

• 24 Aug 08
  

  Martin Carel
  • This leaves us with the problem of avoiding the star in the "select *" that AR generates. For this as well, there is an option to find(): the find method accepts an option hash as its final parameter, and that option has not only allows for the usual :conditions, :order or :limit options, but also for ":select => [ fieldlist ]".
  • Inside the database, this becomes a table definition with VARCHAR(255) columns of the default character set - in many MySQL installations that is utf8.
  • AR cannot specify the database character set in its "create_database" method. So the default value from charset_server is being used. Make sure that in your server this is set to "latin1" or any other single byte character set - never use utf8 by default. Alternatively, specify each "create_table" with an :option => "engine = innodb charset latin1" or similar to avoid using utf8 as a default
  • You should also specify a :limit clause for each and every string, limiting the length of the string to something useful and avoiding the wasteful VARCHAR(255).
  • RoR really should make all values it uses as primary keys and foreign keys UNSIGNED by default.
  • By default, RoR will also create an id column in memberships, which is useless, and not create a unique constraint or even primary key for ( user_id, class_id) which expresses the fact that each user can only be a member in each class once.
     
     "add_index(:memberships, [:user_id, :class_id], :unique => true)" will create such a compound unique index.
  • Since all attributes in AR are always wrapped in accessor methods, it would be easy to keep change flags for all fields and generate minimal UPDATE statements. It would even be possible to forgo the statement completely if nothing has been changed.
  • Apparently Ruby uses InnoDB by default. Apparently Ruby uses transactions a lot. That means that the query cache is of very limited use, because queries inside a transaction cannot use the query cache.
    
  • If a FOREIGN KEY constraint is defined on a table, any insert, update, or delete that requires the constraint condition to be checked sets shared record-level locks on the records that it looks at to check the constraint. InnoDB also sets these locks in the case where the constraint fails.

  7 more annotations...

• 23 Aug 08
  

  Pistos Christou

  ruby rails activerecord mysql database problems issues

• 08 Apr 08
  

  Piotr Golabek

  webapp_blogs

• 07 Jan 08
  

  Sean O'Halpin

  Some interesting observations on ActiveRecord and mysql

  rails mysql activerecord

• 11 Aug 07
  

  miles woodroffe

  mysql rails performance

• 23 Jul 07
  

  Łukasz Piestrzeniewicz

  mysql rubyonrails performance

• 

  Chu Yeow Cheah

  ruby rails mysql

• 22 Jul 07
  

  Geoffrey Bilder

  Inefficient RAILS queries

  rails

• 21 Jul 07
  

  Jason May

  rails performance mysql

• 

  Nicolas Perriault

  This article is about Ruby On Rails and its interaction with MySQL in general.

  mysql rails ruby performance activerecord database optimization clevermarks

• 

  This article is about Ruby On Rails and its interaction with MySQL in general.

  mysql rails ruby performance activerecord database optimization clevermarks

• 

  Adam McCrea

  ruby rails mysql performance activerecord

• 

  mysql rails

• 

  mysql rails

• 20 Jul 07
  

  Mathieu Martin

  Discussion of different possible optimizations for Rails sites using MySQL as a back-end

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• 

  Phil Despotos

  roundup of issues with activerecord

  rails mysql activerecord problems

• 

  tosh .

  Interesting article about Active Record, MySQL and possible ways to improve performance. The comments are pretty interesting too.

  ruby rails active record mysql

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