What is the difference between $ vs $$ Informatica parameters?

Question

What is the difference between $myvar and $$myvar parameters in Informatica PowerCenter?

Answer 1

Actually $ means internal Parameter/Variable (such as $DBConnection prefix or $PMSessionLogDir) whereas $$ are used for user-defined parameters or variables (which could be defined at mapping or workflow/worklet level).

You can declare and use variables and parameters starting with $$ You can override and use pre-defined parameters starting with $PM* (i.e. $PMSessionLogDir, $PMWorkflowLogCount) You can use without declaration parameters following predefined templates (i.e. $InputFile, $DBConnection, etc.).

Answer 2

$ - These are the system variables/Session Parameters like $Bad file, $input file, $output file, $DB connection, $source, $target etc.
$$ - User defined variables/Mapping Parameters like $$State, $$SRC, $$Time, $$Entity, $$Business_Date etc.
You can create a mapping variable/parameter with the name of $$myvar to pass the value in the mapping.