SQL & PHP – Which is faster mysql_num_rows() or ‘select count()’?

by

mysql_query() transfers all result records from the MySQL into the php pcrocess before it returns (unlike mysql_unbufferd_query()). That alone would make the mysql_num_rows() version slower.

Furthermore for some engines (like MyISAM) MySQL can serve a Count(*) request from the index of the table without hitting the actual data. A SELECT * FROM foo on the other hand results in a full table scan and MySQL has to read every single dataset.

More Related Contents:

  1. Query database then email posts from where user is subbed to
  2. check if link “still” exists [duplicate]
  3. Can I parameterize the table name in a prepared statement?
  4. What is parameterized query?
  5. Getting raw SQL query string from PDO prepared statements
  6. Correct way to use LIKE ‘%{$var}%’ with prepared statements?
  7. MySQL Prepared statements with a variable size variable list
  8. Why is require_once so bad to use?
  9. How to replace MySQL functions with PDO?
  10. Insert query on page load, inserts twice?
  11. How to clear APC cache entries?
  12. CakePHP find method with JOIN
  13. Getting HTTP code in PHP using curl
  14. SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax — PHP — PDO [duplicate]
  15. Which is Faster and better, Switch Case or if else if?
  16. PHP – Import CSV file to mysql database Using LOAD DATA INFILE
  17. What is the fastest XML parser in PHP?
  18. How to avoid code repetition with PHP SQL prepared statements?
  19. How to use PHP to connect to sql server
  20. Execute raw SQL using Doctrine 2
  21. Simple PHP SQL login troubleshooting
  22. Change date format (in DB or output) to dd/mm/yyyy – PHP MySQL
  23. Laravel Eloquent get results grouped by days
  24. How does array_diff work?
  25. Log the actual SQL query using ActiveRecord with Yii2?
  26. How to check if a value already exists to avoid duplicates?
  27. Limit download speed using PHP
  28. MYSQL select a piece of a string and order by that piece
  29. PHP/MySQL Pagination
  30. Limit pagination page number

Leave a Comment