| Type: | integer |
| Default: | -1 (-1) |
| Min: | -1 (-1) |
| Max: | 2147483647 (2147483647kB) |
| Unit: | KB |
| Context: | superuser |
| Restart: | false |
| Since: | 9.2 |
Specifies the maximum amount of disk space that a process can use for temporary files, such as sort and hash temporary files, or the storage file for a held cursor. A transaction attempting to exceed this limit will be canceled. If this value is specified without units, it is taken as kilobytes. -1 (the default) means no limit. Only superusers and users with the appropriate SET privilege can change this setting.
This setting constrains the total space used at any instant by all temporary files used by a given PostgreSQL process. It should be noted that disk space used for explicit temporary tables, as opposed to temporary files used behind-the-scenes in query execution, does not count against this limit.
Recommendations
… or something which is bigger than your largest possible sort, but not big enough to run you out of disk space.