select OBJECT_INSTANCE_BEGIN, THREAD_ID, SOCKET_ID, IP, PORT
from performance_schema.socket_instances
limit 1
into @oib, @tid, @sid, @ip, @port;

====================================================================
Testing index for columns OBJECT_INSTANCE_BEGIN
====================================================================
############ Explain for Query ####################################
explain select COUNT(*) 
from performance_schema.socket_instances 
where OBJECT_INSTANCE_BEGIN = "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 COUNT(*)
from performance_schema.socket_instances
where OBJECT_INSTANCE_BEGIN > "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ALL	PRIMARY	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where OBJECT_INSTANCE_BEGIN < "2";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ALL	PRIMARY	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where OBJECT_INSTANCE_BEGIN = @oib;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	const	PRIMARY	PRIMARY	8	const	#	100.00	NULL
############# Explain End #########################################
flush status;
select COUNT(*)
from performance_schema.socket_instances
where OBJECT_INSTANCE_BEGIN = @oib;
COUNT(*)
#
OK: handler_read_key incremented

====================================================================
Testing index for columns THREAD_ID
====================================================================
############ Explain for Query ####################################
explain select COUNT(*) 
from performance_schema.socket_instances 
where THREAD_ID = "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	THREAD_ID	THREAD_ID	9	const	#	100.00	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where THREAD_ID > "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ALL	THREAD_ID	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where THREAD_ID < "2";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ALL	THREAD_ID	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where THREAD_ID = @tid;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	THREAD_ID	THREAD_ID	9	const	#	100.00	Using where
############# Explain End #########################################
flush status;
select COUNT(*)
from performance_schema.socket_instances
where THREAD_ID = @tid;
COUNT(*)
#
OK: handler_read_key incremented

====================================================================
Testing index for columns SOCKET_ID
====================================================================
############ Explain for Query ####################################
explain select COUNT(*) 
from performance_schema.socket_instances 
where SOCKET_ID = "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	SOCKET_ID	SOCKET_ID	4	const	#	100.00	NULL
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where SOCKET_ID > "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ALL	SOCKET_ID	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where SOCKET_ID < "2";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ALL	SOCKET_ID	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where SOCKET_ID = @sid;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	SOCKET_ID	SOCKET_ID	4	const	#	100.00	NULL
############# Explain End #########################################
flush status;
select COUNT(*)
from performance_schema.socket_instances
where SOCKET_ID = @sid;
COUNT(*)
#
OK: handler_read_key incremented

====================================================================
Testing index for columns IP, PORT
====================================================================
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP = "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	IP	IP	258	const	#	100.00	NULL
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP > "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ALL	IP	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP < "2";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ALL	IP	NULL	NULL	NULL	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP = @ip;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	IP	IP	258	const	#	100.00	NULL
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP = "impossible"
    and PORT = "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	IP	IP	262	const,const	#	100.00	NULL
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP = @ip
and PORT = "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	IP	IP	262	const,const	#	100.00	NULL
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP = @ip
and PORT > "impossible";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	IP	IP	258	const	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP = @ip
and PORT < "2";
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	IP	IP	258	const	#	33.33	Using where
############ Explain for Query ####################################
explain select COUNT(*)
from performance_schema.socket_instances
where IP = @ip
and PORT = @port;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	socket_instances	NULL	ref	IP	IP	262	const,const	#	100.00	NULL
############# Explain End #########################################
flush status;
select COUNT(*)
from performance_schema.socket_instances
where IP = @ip
and PORT = @port;
COUNT(*)
#
OK: handler_read_key incremented