37 lines
1.8 KiB
Plaintext
37 lines
1.8 KiB
Plaintext
|
|
====================================================================
|
|
Testing index for columns EVENT_NAME
|
|
====================================================================
|
|
############ Explain for Query ####################################
|
|
explain select COUNT_STAR
|
|
from performance_schema.file_summary_by_event_name
|
|
where EVENT_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 COUNT_STAR
|
|
from performance_schema.file_summary_by_event_name
|
|
where EVENT_NAME > "impossible";
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE file_summary_by_event_name NULL ALL PRIMARY NULL NULL NULL # 33.33 Using where
|
|
############ Explain for Query ####################################
|
|
explain select COUNT_STAR
|
|
from performance_schema.file_summary_by_event_name
|
|
where EVENT_NAME < "2";
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE file_summary_by_event_name NULL ALL PRIMARY NULL NULL NULL # 33.33 Using where
|
|
############ Explain for Query ####################################
|
|
explain select COUNT_STAR
|
|
from performance_schema.file_summary_by_event_name
|
|
where EVENT_NAME = "wait/io/file/sql/ERRMSG";
|
|
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
|
|
1 SIMPLE file_summary_by_event_name NULL const PRIMARY PRIMARY 514 const # 100.00 NULL
|
|
############# Explain End #########################################
|
|
flush status;
|
|
select COUNT_STAR
|
|
from performance_schema.file_summary_by_event_name
|
|
where EVENT_NAME = "wait/io/file/sql/ERRMSG";
|
|
COUNT_STAR
|
|
#
|
|
OK: handler_read_key incremented
|