One would wonder what the title means. Well it was a thunder bolt for me when I was trying to optimize some headless scripts. Well we at Saturn do heavily use headless scripts written in php. Some use mysql some use xml and some other use memcache, in fact pretty much all would use memcache. But that is not the situation now.
In an attempt to multi thread a cron job part of optimizations done an year back, instead of sequential processing, we had switched it to single row processing. Which required to have a method getNextRow which was passed a parameter, the primary key of the table. The cron starts with a value 0 (zero) and after each is processed, the value is supplied as the last processed one. The getNextRow had
select ID from [table] WHERE ID > [LAST_ID] ORDER BY ID ASC LIMIT 1;
Continue reading “SQL – Always use aggregate functions if you can”