Oracle 5.0 Reference Manual page 522

The maximum size of internal in-memory temporary tables. (The actual limit is determined as the
minimum of
tmp_table_size
temporary table exceeds the limit, MySQL automatically converts it to an on-disk
Increase the value of
if you do many advanced
apply to user-created
You can compare the number of internal on-disk temporary tables created to the
total number of internal temporary tables created by comparing the values of the
Created_tmp_disk_tables
See also Section 8.8.5, "How MySQL Uses Internal Temporary
• [502]
tmpdir
Command-Line Format
Option-File Format
Option Sets Variable
Variable Name
Variable Scope
Dynamic Variable
The directory used for temporary files and 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, NetWare, and OS/2.
The multiple-directory feature can be used to spread the load between several physical disks. If
the MySQL server is acting as a replication slave, you should not set
a directory on a memory-based file system or to a directory that is cleared when the server host
restarts. A replication slave needs some of its temporary files to survive a machine restart so that
it can replicate temporary tables or
directory are lost when the server restarts, replication fails. You can set the slave's temporary
directory using the
slave_load_tmpdir
general [502]
tmpdir
•
transaction_alloc_block_size
Command-Line Format
Option-File Format
Option Sets Variable
Variable Name
Variable Scope
Dynamic Variable
Server System Variables
Range
1024 .. 4294967295
[501] and
max_heap_table_size
[501]
tmp_table_size
queries and you have lots of memory. This variable does not
GROUP BY
tables.
MEMORY
[524] and
Created_tmp_tables
--tmpdir=path
-t
tmpdir
Yes, [502]
tmpdir
tmpdir
Global
No
Permitted Values
Type
file name
LOAD DATA INFILE
[1465]
value and you can set
[502]
--transaction_alloc_block_size=#
transaction_alloc_block_size
Yes,
transaction_alloc_block_size
transaction_alloc_block_size
Global, Session
Yes
Permitted Values
Platform
32
Bit Size
Type
numeric
502
(and
max_heap_table_size
[524]
Tables".
operations. If files in the temporary file
variable. In that case, the slave will not use the
[502] to a nonpermanent location.
tmpdir
[468].) If an in-memory
table.
MyISAM
[468] if necessary)
variables.
[502] to point to
tmpdir
[502]