Limits for Hash and Join Indexes
These 32 indexes can be any combination of secondary, hash, and join indexes, including 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.
This also means that a join index cannot have a geospatial NUSI.
Join index columns can have Period data types and can include expressions composed of system and user-defined functions and methods, including the use of the BEGIN, END, and P_INTERSECT built‑in functions on a Period data type column to compose an expression in the projection list and a single‑table condition in its WHERE or ON clauses.
Consult the following manuals for more detailed information on creating and using join indexes to enhance the performance of your database applications: