You can use a Table Refresh to return index information for all DBMS types. For available and sending tables that are defined with indexes, the Connect CDC Director displays each index’s name, its uniqueness (the term “UNIQUE” or “NON-UNIQUE”), and the names of the columns that are part of it. See Refresh the available tables cache.
Two areas in which the display of the indexes may be helpful:
The columns you select as distribution key columns on the Sending Table Properties, Columns page must be primary key columns or columns that constitute a unique constraint.
The Connect CDC Director considers unique indexes as well as primary keys in its determination of distribution keys in default column mappings. If a primary key is defined for the table, it is used. If the table has no primary key but at least one unique index, the first unique index defined for the table is used as if it were a primary key.