FREESPACE PERCENT and DATABLOCK Options | ALTER TABLE | Teradata Vantage - 17.10 - FREESPACE PERCENT - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - SQL Data Definition Language Detailed Topics

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1184-171K
Language
English (United States)

Specify this option to modify the free space percentage for a table.

Not all database operations honor the freespace percentage you specify in an ALTER TABLE request. See the table in the topic FREESPACE PERCENT for lists of which operations honor the specified freespace percentage and which do not.
Do not use the Ferret utility PACKDISK command to change this value once you have created a table or have modified its FREESPACE PERCENT with an ALTER TABLE request.

Instead, submit an ALTER TABLE request to change the free space percent value for the table and then immediately afterward submit a PACKDISK command that specifies the same free space percent value you set with that ALTER TABLE request (see the documentation for the Ferret utility in Teradata Vantage™ - Database Utilities, B035-1102 for more information and instructions for running PACKDISK).

The reason for this is as follows: if you manually submit a PACKDISK command and specify a free space percentage on the command line, PACKDISK packs or unpacks the cylinders for the table to match the specified free space percentage. However, if the free space percentage you specify differs from the value specified for the table when it was created or most recently altered, the database starts a new AutoCylPack task immediately after PACKDISK completes, and this AutoCylPack operation nullifies the free space percentage you had just specified with PACKDISK to realign it with the free space percentage specified when you created or last altered the table.