Back in 2013, MDEV-4016 was posted , and marked resolved in 10.0.4. Temporary tables are being created on disk and not cleaned up.

We are seeing this behavior in 10.1.35.

I posted a comment on the closed but, but I suspect that was not the correct way to raise the issue, since it got no comments. Here it is in a new bug.

My server was restarted on 2019-02-16. On 2019-02-20, it had over 43000 files in the temp directory, in the format of #sqlxxxx_xxx_0.ibd. Example. The oldest file in my tmp directory is

rw-rw--- 1 mysql mysql 9437184 Feb 16 21:07 #sql1c3d_72fa_0.ibd

Then:
lsof|grep sql1c3d_72fa_0.ibd
produces 38 lines of open file output for the same filename:

lsof|grep sql1c3d_72fa_0.ibd
mysqld 7229 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7311 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7312 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7354 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7355 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7356 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7357 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7358 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7359 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7360 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7361 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7362 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7363 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7364 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7526 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7527 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7528 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7529 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7530 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7531 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7533 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7534 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7535 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7536 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7537 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7568 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 7757 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 21398 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 23732 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 23903 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 23972 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 23985 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 24067 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 24324 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 24508 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd
mysqld 7229 24510 mysql 527uW REG 253,2 9437184 7864327 /mariadb_tmp/#sql1c3d_72fa_0.ibd

Then we have a bunch of

Over time, this really can fill up, requiring a server stop/start, which requires notification of outage, and all the procedure that comes with this.

What more information can I provide?

Thanks,
Ed Greenberg