Function format_preparedparamsdata

src/pl/plpgsql/src/pl_exec.c:8696–8736

* Return a formatted string with information about the parameter values, * or NULL if there are no parameters. * The result is in the eval_mcontext. */

 * The result is in the eval_mcontext.
 */
static char *
format_preparedparamsdata(PLpgSQL_execstate *estate,
						  ParamListInfo paramLI)
{
	int			paramno;
	StringInfoData paramstr;
	MemoryContext oldcontext;

	if (!paramLI)
		return NULL;

	oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));

	initStringInfo(&paramstr);
	for (paramno = 0; paramno < paramLI->numParams; paramno++)
	{
		ParamExternData *prm = &paramLI->params[paramno];

		/*
		 * Note: for now, this is only used on ParamListInfos produced by
		 * exec_eval_using_params(), so we don't worry about invoking the
		 * paramFetch hook or skipping unused parameters.
		 */
		appendStringInfo(&paramstr, "%s$%d = ",
						 paramno > 0 ? ", " : "",
						 paramno + 1);

		if (prm->isnull)
			appendStringInfoString(&paramstr, "NULL");
		else
			appendStringInfoStringQuoted(&paramstr,
										 convert_value_to_string(estate,
																 prm->value,
																 prm->ptype),
										 -1);
	}

	MemoryContextSwitchTo(oldcontext);

	return paramstr.data;
}