MySQL Performance Blog » COUNT(*) vs COUNT(col) - The Diigo Meta page

• 14 Apr 11
  

  carsten e

  MySQL Perfomence Example of using Count

  MySQL Count Performance

• 17 Dec 10
  

  anycolorilike

  mysql performance sql database

• 14 Sep 09
  

  Lawrence Lagerlof

  Comparação entre a performance do count(*) e count(coluna)

  mysql count versus comparacao comparar

• 19 Jun 08
  

  Navneet Kumar

  count(col) vs count(*)

  MySQL Performance

  • Because val column is not defined as NOT NULL there can be some NULL values in it and so MySQL have to perform table scan to find out.
  • whether or not it is a valuable thing to know the accurate number of rows in an entire table at any time
• 13 Feb 08
  

  lucasarruda

  mysql database performance sql count tips innodb development

• 05 Aug 07
  

  rafaelsteil

  Looking at how people are using COUNT(*) and COUNT(col) it looks like most of them think they are synonyms and just using what they happen to like, while there is substantial difference in performance and even query result.

  mysql database db count performance innodb myisam select

• 16 Apr 07
  

  kixxtm

  mysql database devel performance sql

Would you like to comment?

Join Diigo for a free account, or sign in if you are already a member.