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select connection_id() into @conid;
select thread_id from performance_schema.threads
where PROCESSLIST_ID = @conid
into @tid;
====================================================================
Testing index for columns THREAD_ID, ERROR_NUMBER
====================================================================
############ Explain for Query ####################################
explain select SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID = "impossible";
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE events_errors_summary_by_thread_by_error NULL ref THREAD_ID THREAD_ID 8 const # 100.00 Using where
############ Explain for Query ####################################
explain select SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID > "impossible";
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE events_errors_summary_by_thread_by_error NULL ALL THREAD_ID NULL NULL NULL # 33.33 Using where
############ Explain for Query ####################################
explain select SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID < "2";
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE events_errors_summary_by_thread_by_error NULL ALL THREAD_ID NULL NULL NULL # 33.33 Using where
############ Explain for Query ####################################
explain select SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID = @tid;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE events_errors_summary_by_thread_by_error NULL ref THREAD_ID THREAD_ID 8 const # 100.00 NULL
############ Explain for Query ####################################
explain select SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID = "impossible"
and ERROR_NUMBER = "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 SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID = @tid
and ERROR_NUMBER = "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 SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID = @tid
and ERROR_NUMBER > "impossible";
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE events_errors_summary_by_thread_by_error NULL ref THREAD_ID THREAD_ID 8 const # 33.33 Using where
############ Explain for Query ####################################
explain select SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID = @tid
and ERROR_NUMBER < "2";
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE events_errors_summary_by_thread_by_error NULL ref THREAD_ID THREAD_ID 8 const # 33.33 Using where
############ Explain for Query ####################################
explain select SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID = @tid
and ERROR_NUMBER = "1146";
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE events_errors_summary_by_thread_by_error NULL const THREAD_ID THREAD_ID 13 const,const # 100.00 NULL
############# Explain End #########################################
flush status;
select SUM_ERROR_RAISED
from performance_schema.events_errors_summary_by_thread_by_error
where THREAD_ID = @tid
and ERROR_NUMBER = "1146";
SUM_ERROR_RAISED
#
OK: handler_read_key incremented
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