Hello, some simple query are very slow since a few days, no significant changes are done the last days. I look for disk-io, swap, looked tables, all seems to be good. What I have found is this: postgres=# SELECT temp_files AS "Temporary files" , temp_bytes AS "Size of temporary files" FROM pg_stat_database db; Temporary files | Size of temporary files -----------------+------------------------- 0 | 0 0 | 0 0 | 0 0 | 0 13542 | 5313912899891 (5 rows) postgres@dolly:~/9.6/main/base/pgsql_tmp$ ls -la total 20 drwx------ 2 postgres postgres 16384 Feb 3 02:25 . drwx------ 8 postgres postgres 4096 Jul 26 2017 .. Where does the 13542 tmp files are come from? How can I delete that? Where are they stored?