Why do we create volatile table?

Volatile Table. Volatile tables are created, used and dropped within a user session. Their definition is not stored in data dictionary. They hold intermediate data of the query which is frequently used.

What’s a volatile table?

Teradata Volatile tables act like a normal Teradata table but are volatile in nature. What does that mean? The Volatile tables in Teradata are created by the user and used only the duration they are logged into the Teradata system and dropped automatically by Teradata Manager once the user disconnects from the session.

What is the difference between global temporary tables and volatile temporary tables?

Index can be created on Global Temporary table and not on Volatile table. Global temporary table uses Temporary space of login user and Volatile table uses spool space of login userIn a single session 2000 Global temporary table can be materialized and 1000 Volatile tables can be materialized.

Can we collect stats on volatile table?

Can I create statistics on a volatile table? Statistics are allowed, but when using the statement DIAGNOSTIC HELPSTAT ON FOR SESSION, we have to be aware that they are still proposed in the EXPLAIN plan.

How do volatile tables work?

A volatile table is a temporary table that is only held until the end of session. This is created by default in your “personal schema” and consumes your spool space to maintain.

What is the significance of on commit preserve rows while creating volatile table?

Yes. You cannot see the records because Teradata becomes strict to VOLATILE tables by incorporating ON COMMIT DELETE ROWS by default to add more meaning to VOLATILE. so, if you want to see the records you have to explicitly write ON COMMIT PRESERVE ROWS immediately after CREATE TABLE syntax.

What is volatile table in db2?

A table is defined as volatile when it is altered or created with VOLATILE attribute: db2 alter table VOLATILE. This means that the numbers of records in the table varies significantly from 0 to large number pretty often.

Is Volatile table set or multiset?

1 Answer. Volatile table is like work table in SAS, it just is there for particular session. Teradata has 2 kinds of table, one is set table and another is multiset table. Set table does not allow row level duplicates, where multiset table allows row level duplicates.

What is multiset volatile table in Teradata?

Volatile table in Teradata is used to store data temporarily in a session. The table will be destroyed when the session ends. The content of the table can be deleted after each journal step depends on the definition of the table and transaction mode. Volatile table will be stored in the login user database.

What is CTE in Teradata?

In Teradata, Common Table Expression (CTE) is supported as other databases. You can create recursive CTE or use a reference of a CTE to another CTE. However there is a slight differences compared with other databases – The referenced CTE must be present after the referencing CTE.

Why do we use collect stats in Teradata?

The COLLECT STATISTICS (Optimizer form) statement collects demographic data for one or more columns of a base table, hash index, or join index, computes a statistical profile of the collected data, and stores the synopsis in the Data Dictionary.

What is a volatile table in SQL?

What is volatile table in SQL Server?

Volatile tables are used to store some data which is session specific and we need not store that data persistently. Once the session is over, all the data and table definition is lost. Volatile Tables use SPOOL SPACE. We can create a VOLATILE table by using below minimal syntax:

What is volatile table in Teradata?

Volatile tables are session-specific tables which stores intermediate data and once the session is over, all the data and table definition is removed. Volatile Tables uses SPOOL SPACE. In Teradata, use keyword “VOLATILE” in CREATE statement to create a volatile table.

How to improve performance of a volatile table?

If Volatile table is created with LOG option, then it will use Transient Journal to save “BEFORE IMAGES” of all the transactions. Since the data is intermediate and can be generated again in case of failures I strongly recommend to go ahead with NO LOG option. This is one simple thing you can do to improve performance of volatile tables.

Where are volatile tables materialized?

Volatile Tables are materialized in the spool space of the user. Who can access a Volatile Table? Volatile tables can only be accessed in the user’s session in which they were materialized. Is there a DBC table where I can see which Volatile Tables I have materialized?