Server System Variables • tmpdir Command-Line Format --tmpdir=dir_name System Variable tmpdir Scope Global Dynamic No SET_VAR  Hint Applies No Type Directory name The path of the directory to use for creating temporary files. It might be useful if your default  /tmp directory resides on a partition that is too small to hold temporary tables. This variable can be set to a list of several paths that are used in round-robin fashion. Paths should be separated by colon characters ( : ) on Unix and semicolon characters ( ; ) on Windows. tmpdir  can be a non-permanent location, such as a directory on a memory-based file system or a directory that is cleared when the server host restarts. If the MySQL server is acting as a replica, and you are using a non-permanent location for  tmpdir , consider setting a different temporary directory for the replica using the  slave_load_tmpdir  variable. For a replica, the temporary files used to replicate LOAD DATA  statements are stored in this directory, so with a permanent location they can survive machine restarts, although replication can now continue after a restart if the temporary files have been removed. For more information about the storage location of temporary files, see Section B.3.3.5, “Where MySQL Stores Temporary Files” . Command-Line Format --transaction-alloc-block-size=# System Variable transaction_alloc_block_size Scope Global, Session Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 8192 Minimum Value 1024 Maximum Value 131072 Block Size 1024 The amount in bytes by which to increase a per-transaction memory pool which needs memory. See the description of  transaction_prealloc_size . Command-Line Format --transaction-isolation=name System Variable transaction_isolation Scope Global, Session Dynamic Yes 909 • transaction_isolation • transaction_alloc_block_size