Database Error Messages

Release
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  • 23ai
  • 21c
  • 19c
Updated
Jun 24, 2024

ORA-01404

ALTER COLUMN will make an index too large

Cause

Increasing the length of a column would cause the combined length of the columns specified in a previous CREATE INDEX statement to exceed the maximum index length (255). The total index length was computed as the sum of the width of all indexed columns plus the number of indexed columns. Date fields were calculated as a length of 7, character fields were calculated at their defined width, and numeric fields were length 22.


Action

The only way to alter the column is to drop the affected index. The index cannot be re-created if to do so would exceed the maximum index width.