The following restrictions apply to secondary indexes.
This includes the system‑defined secondary indexes used to implement PRIMARY KEY and UNIQUE constraints.
Each multicolumn NUSI that specifies an ORDER BY clause counts as two consecutive indexes in this calculation (see “Importance of Consecutive Indexes for Value‑Ordered NUSIs” on page 485).
You cannot define secondary indexes for a global temporary trace table. See “CREATE GLOBAL TEMPORARY TRACE TABLE” in SQL Data Definition Language.
You can define a simple NUSI on a geospatial column, but you cannot include a column having a geospatial data type in a composite NUSI definition or in a USI definition.