Explains what the feature is or what its benefits are to the user or customer.
You can remove a column from a data source, even if its data load has been run in the past, by using this procedure.
- Log in to the Linux shell using SSH.
- Launch TQL.
- Designate the database you'll be working in:
TQL> use <database_name>;
- Find the name of the table you want to change.You can use the TQL command
SHOW TABLES;to see a list of tables.
To see the current sharding on the table, use
SCRIPT TABLE <table_name>;
- Issue the command to remove the column from the table using this syntax:
TQL> ALTER TABLE <schema>.<table> DROP COLUMN <column>;For example, to drop the column "account_id" from the table "account" in the schema "foodmart":
TQL> ALTER TABLE foodmart.account DROP COLUMN account_id;You must use the fully qualified name of the old table when adding the column via TQL. To find that you can look at the DDL for the data source job itself.
- Run the
SCRIPT TABLEcommand to get the new DDL to create the table.
TQL> SCRIPT TABLE <table>;
Copy the output of the command. Replace any VARCHAR(<number) column definitions with VARCHAR(0), to match the DDL that Data Connect generates. This is the DDL that you will use in your new data source.
- Create a new data source.Be sure to choose the correct columns to match the new target table columns definitions. When you reach the step about editing the generated schema DDL, paste in the DDL that was output by the
- Run the data load and verify that everything is working as it should be.
- If the old data source was running as a recurring load, stop it from running.