A temporary table is used by an access plan to store data during its execution in a transient or temporary work table. This table only exists while the access plan is being executed. Generally, temporary tables are used when subqueries need to be evaluated early in the access plan, or when intermediate results do not fit in the available memory.
You can avoid using temporary tables by using an index for the columns used in the ORDER BY or GROUP BY clauses. If you do not use an index, the temporary file holds information used by UltraLite during query processing.
Data in a temporary table is held for a single connection only. Temporary tables consist of rows and columns. Each column carries a particular kind of information, such as a phone number or a name, while each row specifies a particular entry.