pg_proc
   The catalog pg_proc stores information about
   functions, procedures, aggregate functions, and window functions
   (collectively also known as routines).  See CREATE FUNCTION, CREATE PROCEDURE, and
   Section 38.3 for more information.
  
   If prokind indicates that the entry is for an
   aggregate function, there should be a matching row in
   pg_aggregate.
  
Table 52.39. pg_proc Columns
| Name | Type | References | Description | 
|---|---|---|---|
| oid | oid | Row identifier (hidden attribute; must be explicitly selected) | |
| proname | name | Name of the function | |
| pronamespace | oid |  | The OID of the namespace that contains this function | 
| proowner | oid |  | Owner of the function | 
| prolang | oid |  | Implementation language or call interface of this function | 
| procost | float4 | Estimated execution cost (in units of
       cpu_operator_cost); if proretset,
       this is cost per row returned | |
| prorows | float4 | Estimated number of result rows (zero if not proretset) | |
| provariadic | oid |  | Data type of the variadic array parameter's elements, or zero if the function does not have a variadic parameter | 
| protransform | regproc |  | Calls to this function can be simplified by this other function (see Section 38.10.10) | 
| prokind | char | ffor a normal function,pfor a procedure,afor an aggregate function, orwfor a window function | |
| prosecdef | bool | Function is a security definer (i.e., a “setuid” function) | |
| proleakproof | bool | The function has no side effects. No information about the arguments is conveyed except via the return value. Any function that might throw an error depending on the values of its arguments is not leak-proof. | |
| proisstrict | bool | Function returns null if any call argument is null. In that case the function won't actually be called at all. Functions that are not “strict” must be prepared to handle null inputs. | |
| proretset | bool | Function returns a set (i.e., multiple values of the specified data type) | |
| provolatile | char | provolatiletells whether the function's
       result depends only on its input arguments, or is affected by outside
       factors.
       It isifor “immutable” functions,
       which always deliver the same result for the same inputs.
       It issfor “stable” functions,
       whose results (for fixed inputs) do not change within a scan.
       It isvfor “volatile” functions,
       whose results might change at any time.  (Usevalso
       for functions with side-effects, so that calls to them cannot get
       optimized away.) | |
| proparallel | char | proparalleltells whether the function
       can be safely run in parallel mode.
       It issfor functions which are safe to run in
       parallel mode without restriction.
       It isrfor functions which can be run in parallel
       mode, but their execution is restricted to the parallel group leader;
       parallel worker processes cannot invoke these functions.
       It isufor functions which are unsafe in parallel
       mode; the presence of such a function forces a serial execution plan. | |
| pronargs | int2 | Number of input arguments | |
| pronargdefaults | int2 | Number of arguments that have defaults | |
| prorettype | oid |  | Data type of the return value | 
| proargtypes | oidvector |  | An array with the data types of the function arguments.  This includes
       only input arguments (including INOUTandVARIADICarguments), and thus represents
       the call signature of the function. | 
| proallargtypes | oid[] |  | An array with the data types of the function arguments.  This includes
       all arguments (including OUTandINOUTarguments); however, if all the
       arguments areINarguments, this field will be null.
       Note that subscripting is 1-based, whereas for historical reasonsproargtypesis subscripted from 0. | 
| proargmodes | char[] | An array with the modes of the function arguments, encoded as iforINarguments,oforOUTarguments,bforINOUTarguments,vforVARIADICarguments,tforTABLEarguments.
        If all the arguments areINarguments,
        this field will be null.
        Note that subscripts correspond to positions ofproallargtypesnotproargtypes. | |
| proargnames | text[] | An array with the names of the function arguments.
        Arguments without a name are set to empty strings in the array.
        If none of the arguments have a name, this field will be null.
        Note that subscripts correspond to positions of proallargtypesnotproargtypes. | |
| proargdefaults | pg_node_tree | Expression trees (in nodeToString()representation)
       for default values.  This is a list withpronargdefaultselements, corresponding to the lastNinput arguments (i.e., the lastNproargtypespositions).
       If none of the arguments have defaults, this field will be null. | |
| protrftypes | oid[] | Data type OIDs for which to apply transforms. | |
| prosrc | text | This tells the function handler how to invoke the function. It might be the actual source code of the function for interpreted languages, a link symbol, a file name, or just about anything else, depending on the implementation language/call convention. | |
| probin | text | Additional information about how to invoke the function. Again, the interpretation is language-specific. | |
| proconfig | text[] | Function's local settings for run-time configuration variables | |
| proacl | aclitem[] | Access privileges; see GRANT and REVOKE for details | 
   For compiled functions, both built-in and dynamically loaded,
   prosrc contains the function's C-language
   name (link symbol).  For all other currently-known language types,
   prosrc contains the function's source
   text.  probin is unused except for
   dynamically-loaded C functions, for which it gives the name of the
   shared library file containing the function.