UDx restrictions

Some UDx types have special considerations or restrictions.

UDxs written in Java and R do not support complex types.

Aggregate functions

You cannot use the DISTINCT clause in queries with more than one aggregate function or provide inputs or return values containing complex types.

Analytic functions

UDAnFs do not support framing windows using ROWS.

Only UDAnFs written in C++ can use complex types.

As with Vertica's built-in analytic functions, UDAnFs cannot be used with MATCH clause functions.

Scalar functions

If the result of applying a UDSF is an invalid record, COPY aborts the load even if CopyFaultTolerantExpressions is set to true.

A ROW returned from a UDSF cannot be used as an argument to COUNT.

Transform functions

A query that includes a UDTF cannot:

• Include statements other than the SELECT statement that calls the UDTF and a PARTITION BY expression unless the UDTF is marked as a one-to-many UDTF

• Call an analytic function

• Call another UDTF

• Include one of the following clauses:

  • TIMESERIES

  • Pattern matching

  • Gap filling and interpolation

Load functions

Installing an untrusted UDL function can compromise the security of the server. UDxs can contain arbitrary code. In particular, user-defined parser functions can read data from any arbitrary location. It is up to the developer of the function to enforce proper security limitations. Superusers must not grant access to UDxs to untrusted users.

You cannot ALTER UDL functions.

UDFilter and UDSource functions do not support complex types.