IDO SQL Query - Copying to tmp table - Filled up /tmp


I came across a Select SQL query being made by Master ( seen in ‘processlist’ ) to the DB creating 2 “#sql…MYx” files in /tmp. One of them was 77GB. After checking a day after, the files no longer exists and the query was not running. Based on the recent history, it does seem to use all /tmp space and mysqld.log did show the errors to repair the files which I think because there was no space left in /tmp.

I’m wondering what that query is for and why it created those files ? I gathered that a temp table may have been created under /tmp by the query. As per the file name, it seems the tables used “MyISAM” engine. Does that mean Icinga2/IDO use “MyISAM” engine to create a temp table?
All the tables of Icinga2 IDO and Icingaweb2 are using “InnoDB”

I can provide that query when I get to it soon.

Any idea what Icinga2 might have been running that query for?

icinga_ido | Query       |  2262125 | Copying to tmp table                                                  | SELECT COUNT(*) AS cnt FROM (SELECT h.display_name COLLATE latin1_general_ci AS host_display_name, h |