log_slow_filter = not_using_index set automatically log_queries_not_using_indexes = 1 and overwrites long_query_time filter

In

https://mariadb.com/kb/en/server-system-variables/#log_slow_filter

is documented

" If a query matches one of the types listed in the filter, and takes longer than long_query_time, it will be logged"

So long_query_time is a mandatory condition for log_slow_filter.

So log_slow_filter and log_slow_filter must be fulfilled.

But this is not the case for option
"not_using_index".

If you add "not_using_index" to log_slow_filter
it logs into slow_log, even if the execution time is less than "log_slow_filter" long_query_time.

The root cause is, that adding
"not_using_index"
to "log_slow_filter"
set implicit log_queries_not_using_indexes = 1.

to reproduce:

set SESSION  log_queries_not_using_indexes = 0;

SHOW VARIABLES LIKE 'log_q%';

set SESSION log_slow_filter  = "admin,filesort,filesort_on_disk,filesort_priority_queue,full_join,full_scan,not_using_index,query_cache,query_cache_miss,tmp_table,tmp_table_on_disk ";

SHOW VARIABLES LIKE 'log_q%';

For "log_queries_not_using_indexes", it is documented,
that query time is not important.

Queries that don't use an index, or that perform a full index scan where the index doesn't limit the number of rows, will be logged to the slow query log (regardless of time taken).

But "not_using_index," as a "log_slow_filter" option should respect "long_query_time".