Re: Creating Sort Index Slow

[Rick James]

> max_connections=10000

Excessive. Most sites don't need more than 100.

> Select * from artran where type = "SO" order by wos_date desc, refno desc limit 20

SHOW CREATE TABLE artran;

This compound index might help:
INDEX(type, wos_date, refno)

> key_buffer_size=128M

If you are using only MyISAM, change that to 20% of available RAM.

> there have a process of creating sort index which is very slow

Elaborate on what you mean.

> around 20 seconds for the first time and around 5 seconds for the second time.

That speedup is probably due to caching.

> It only happen to myisam table.

InnoDB is preferred. At which point, the most important setting is innodb_buffer_pool_size.