… on AUTO-INC. We have recovered the concurrency and the performance but with a small cost. Queries like INSERT … ON DUPLICATE…=InnoDB; Insert a value using a LEFT OUTER JOIN: insert into foo(name) select 1 from mutex left outer join foo on foo.name=1 where… INSERT IGNORE: insert into foo(name) select 1 from mutex left outer join foo on foo.name=1 where mutex.i = 1 and…
Post: Eventual Consistency in MySQL
November 18, 2011 By 8 Comments
… learn that the enforcement of foreign keys incurs a significant performance overhead.1,2 MySQL allows us to set FOREIGN_KEY… ‘, K.TABLE_SCHEMA, ‘.’, K.TABLE_NAME, ‘ AS ‘, K.CONSTRAINT_NAME, ‘ ‘, ‘LEFT OUTER JOIN ‘, K.REFERENCED_TABLE_SCHEMA, ‘.’, K.REFERENCED_TABLE_NAME, ‘ AS ‘, K…
Comment: A common problem when optimizing COUNT()
September 22, 2008 By 19 Comments
… rows and not values, in the best case it may perform as well as COUNT(*) but never better. What happens when… not better,” what metric of goodness are you using? In performance it can never be better; in optimizability/understandability/maintainability, COUNT…’re trying to count rows. The person who commented about LEFT OUTER JOIN is right on the money, that is the most common…
Post: MySQL VIEW as performance troublemaker
August 12, 2007 By 57 Comments
…outer query and plus if you use more then one Temporary Tables views which you join… blog, naturally containing user_id which left comment, comment_id and comment text: CREATE TABLE `…join” used to to join between them. In this particular case it is not that bad because “join cache” is used to perform…
