This column is no longer used and will be removed in the next release. Use SYSCAT.INDEXCOLUSE for this information.
Other changes in ibm_db_sa may be necessary due to the same backwards-incompatible change in DB2, for example, in get_indexes, which should return the index columns
Reflection wasn't working on DB2 Warehouse on Cloud, and possibly wasn't working with some other recent DB2 versions, which do not have a valid SYSCOL.INDEXES.COLNAMES From the documentation: https://www.ibm.com/support/knowledgecenter/SSEPGG_11.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r0001047.html
Other changes in ibm_db_sa may be necessary due to the same backwards-incompatible change in DB2, for example, in get_indexes, which should return the index columns