Re: SQL_CALC_FOUND_ROWS slow?

[bth505]

Sounds like an un-optimized where query, the joins are most likely not the problem. When using COUNT or SQL_CALC_FOUND_ROWS with a WHERE the mysql server has to process every row. When using a LIMIT the query halts as soon as the max-limit is reached. Depending on the size of the result set this may only process a marginal ammount of the database. If you just need a matches count and a smaller result SQL_CALC_FOUND_ROWS is probably perfect but you must have friendly indexes and WHERE clauses as it reads the entire table. Read more on 'How Mysql optimizes WHERE and ORDER'.