Explicit Procedure - Teradata Vantage

The following table provides a more explicit procedure:

1. Create a new base table on the Teradata platform with a definition that matches the definition for the legacy table as closely as possible.

   Do not define any secondary indexes on this base table at this stage of the process.

2. Use a Teradata load utility to load the newly defined base table with a representative sample of rows from the legacy table. The loaded sample must reflect the demographics of the entire population of the legacy table and be a precise percentage of the cardinality for that table.
3. Query the system view (see Querying DBC.TableSizeV) for the space occupied by the new base table.
4. Record the number of bytes returned by the query.
5. Add a secondary index to the table.
6. Query the system view again for the space occupied by the new base table and the new secondary index.
7. Record the number of bytes returned by the query.
8. The arithmetic difference between the numbers you recorded in step 4 and step 7 is the size of the newly defined secondary index.
9. Iterate step 5 and step 6 until you have finished adding all the secondary indexes you anticipate defining for this table.
10. Repeat the procedure with another legacy table until you have estimated the initial size of your entire database.
11. Evaluate the sizes of any join indexes (and any secondary indexes defined on join indexes) you anticipate using with the new database.