Data Copying

SAP ASE performs a data copy only if it must temporarily copy data out of a table before it changes the table’s schema. If the table has any indexes, SAP ASE rebuilds the indexes when the data copy finishes.

Note: If alter table is performing a data copy, the database that contains the table must have select into/bulkcopy/pllsort turned on. See the Reference Manual: Commands.
SAP ASE performs a data copy when you:
alter table does not perform a data copy when you change the:
To identify if alter table performs a data copy:
  1. Set showplan on to report whether SAP ASE will perform a data copy.

  2. Set noexec on to ensure that no work will be performed.

  3. Perform the alter table command if no data copy is required; only catalog updates are performed to reflect the changes made by the alter table command.