====================================================================
Testing index for columns NAME
====================================================================
############ Explain for Query ####################################
explain select ENABLED 
from performance_schema.setup_threads 
where NAME = "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	#	NULL	no matching row in const table
############ Explain for Query ####################################
explain select ENABLED
from performance_schema.setup_threads
where NAME > "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	setup_threads	NULL	ALL	PRIMARY	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select ENABLED
from performance_schema.setup_threads
where NAME < "2";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	setup_threads	NULL	ALL	PRIMARY	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select ENABLED
from performance_schema.setup_threads
where NAME = "thread/sql/main";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	setup_threads	NULL	const	PRIMARY	PRIMARY	514	const	#	100.00	NULL
############# Explain End #########################################
flush status;
select ENABLED
from performance_schema.setup_threads
where NAME = "thread/sql/main";
ENABLED
#
OK: handler_read_key incremented