Function defGetInt64

src/backend/commands/define.c:189–217

* Extract an int64 value from a DefElem. */

 * Extract an int64 value from a DefElem.
 */
int64
defGetInt64(DefElem *def)
{
	if (def->arg == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("%s requires a numeric value",
						def->defname)));
	switch (nodeTag(def->arg))
	{
		case T_Integer:
			return (int64) intVal(def->arg);
		case T_Float:

			/*
			 * Values too large for int4 will be represented as Float
			 * constants by the lexer.  Accept these if they are valid int8
			 * strings.
			 */
			return DatumGetInt64(DirectFunctionCall1(int8in,
													 CStringGetDatum(strVal(def->arg))));
		default:
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("%s requires a numeric value",
							def->defname)));
	}
	return 0;					/* keep compiler quiet */
}

/*
 * Extract a possibly-qualified name (as a List of Strings) from a DefElem.