As with other functions and operators, Vantage performs implicit conversion of types that are compatible with LOBs according to the rules of precedence. If you define a UDF that declares a LOB type parameter, you can call the UDF and pass a compatible argument.
| Declared Parameter Type | Passed Parameter Type |
|---|---|
| CLOB |
|
| BLOB |
|
Implicit conversions of types compatible with LOBs can have performance consequences.
For example, suppose a UDF declares a BLOB parameter. If you call the UDF and pass in a VARBYTE column, Vantage converts the VARBYTE value to a temporary BLOB and passes the BLOB value to the UDF. Because Vantage stores the temporary BLOB on disk, the performance cost of the conversion is significant.
A solution is to create an overloaded function that explicitly declares a VARBYTE argument.