The configuration community:
read_rnd_buffer_size
Information
When reading rows in sorted order following a key-sorting operation the rows are read through this buffer to avoid disk seeks. Setting the variable to a large value can improve ORDER BY performance by a lot. However this is a buffer allocated for each client so you should not set the global variable to a large value. Instead change the session variable only from within those clients that need to run large queries.
Syntax
Example



