Temporary Tables¶
A Temporary table in Virtual DataPort is a special type of view that only lives for the duration of the session of the user that creates it, or until she deletes it. The view and the data inserted in it are only visible by the user that creates the table.
The data of these tables is stored in the database where the data is cached, instead of in an external data source. Unlike the other types of views, its schema and its data are completely managed from Virtual DataPort.
When you create a temporary table, the Server creates a table (a real table, not a temporary one) in the cache database that will hold the data you insert in it.
You can insert rows into temporary tables but cannot delete or update them.
Note
Before creating any temporary table, enable the cache engine. To do this, follow the steps described in the section Configuring the Cache of the Administration Guide.
The differences between temporary tables and materialized tables are the following:
Temporary Tables |
Materialized Tables |
|---|---|
Only visible by the user that creates the table. |
Visible to all the users with the appropriate privileges. |
Automatically deleted once the user closes the session to the database. I.e. when creating the table from the “VQL Shell” of the Administration Tool, until the user disconnects or switches to another database. |
They are persisted across session. |
Two users may create a temporary table each, both with the same name. Each user will only have access to her own. |
There cannot be two materialized tables with the same name. |
They cannot be created nor managed graphically from the Administration Tool. They can be created only from the “VQL Shell”. |
They cannot be graphically created from the Administration Tool (only from the “VQL Shell”), but after refreshing the Administration Tool (clicking “Refresh” on the “File” menu), they can be managed graphically. |
You cannot create derived views over temporary tables. |
You can create derived views over materialized tables. |
After 48 hours of creating a temporary table, Virtual DataPort removes the table from the database. It does so to prevent that the data of a table is kept in the database indefinitely. This scenario may occur if there is an error while a user closes her session and she has created a table.