Function pg_get_functiondef

src/backend/utils/adt/ruleutils.c:2801–3047

* pg_get_functiondef * Returns the complete "CREATE OR REPLACE FUNCTION ..." statement for * the specified function. * * Note: if you change the output format of this function, be careful not * to break psql's rules (in \ef and \sf) for identifying the start of the * function body. To wit: the function body starts on a line that begins * with "AS ", and no preceding line will look like t

 * with "AS ", and no preceding line will look like that.
 */
Datum
pg_get_functiondef(PG_FUNCTION_ARGS)
{
	Oid			funcid = PG_GETARG_OID(0);
	StringInfoData buf;
	StringInfoData dq;
	HeapTuple	proctup;
	Form_pg_proc proc;
	bool		isfunction;
	Datum		tmp;
	bool		isnull;
	const char *prosrc;
	const char *name;
	const char *nsp;
	float4		procost;
	int			oldlen;

	initStringInfo(&buf);

	/* Look up the function */
	proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
	if (!HeapTupleIsValid(proctup))
		PG_RETURN_NULL();

	proc = (Form_pg_proc) GETSTRUCT(proctup);
	name = NameStr(proc->proname);

	if (proc->prokind == PROKIND_AGGREGATE)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("\"%s\" is an aggregate function", name)));

	isfunction = (proc->prokind != PROKIND_PROCEDURE);

	/*
	 * We always qualify the function name, to ensure the right function gets
	 * replaced.
	 */
	nsp = get_namespace_name(proc->pronamespace);
	appendStringInfo(&buf, "CREATE OR REPLACE %s %s(",
					 isfunction ? "FUNCTION" : "PROCEDURE",
					 quote_qualified_identifier(nsp, name));
	(void) print_function_arguments(&buf, proctup, false, true);
	appendStringInfoString(&buf, ")\n");
	if (isfunction)
	{
		appendStringInfoString(&buf, " RETURNS ");
		print_function_rettype(&buf, proctup);
		appendStringInfoChar(&buf, '\n');
	}

	print_function_trftypes(&buf, proctup);

	appendStringInfo(&buf, " LANGUAGE %s\n",
					 quote_identifier(get_language_name(proc->prolang, false)));

	/* Emit some miscellaneous options on one line */
	oldlen = buf.len;