Function ExecBuildSlotValueDescription

src/backend/executor/execMain.c:3365–3495

* ExecBuildSlotValueDescription -- construct a string representing a tuple * * This is intentionally very similar to BuildIndexValueDescription, but * unlike that function, we truncate long field values (to at most maxfieldlen * bytes). That seems necessary here since heap field values could be very * long, whereas index entries typically aren't so wide. * * Also, unlike the case with inde

 * columns they are.
 */
static char *
ExecBuildSlotValueDescription(Oid reloid,
							  TupleTableSlot *slot,
							  TupleDesc tupdesc,
							  Bitmapset *modifiedCols,
							  int maxfieldlen)
{
	StringInfoData buf;
	StringInfoData collist;
	bool		write_comma = false;
	bool		write_comma_collist = false;
	int			i;
	AclResult	aclresult;
	bool		table_perm = false;
	bool		any_perm = false;

	/*
	 * Check if RLS is enabled and should be active for the relation; if so,
	 * then don't return anything.  Otherwise, go through normal permission
	 * checks.
	 */
	if (check_enable_rls(reloid, InvalidOid, true) == RLS_ENABLED)
		return NULL;

	initStringInfo(&buf);

	appendStringInfoChar(&buf, '(');

	/*
	 * Check if the user has permissions to see the row.  Table-level SELECT
	 * allows access to all columns.  If the user does not have table-level
	 * SELECT then we check each column and include those the user has SELECT
	 * rights on.  Additionally, we always include columns the user provided
	 * data for.
	 */
	aclresult = pg_class_aclcheck(reloid, GetUserId(), ACL_SELECT);
	if (aclresult != ACLCHECK_OK)
	{
		/* Set up the buffer for the column list */
		initStringInfo(&collist);
		appendStringInfoChar(&collist, '(');
	}
	else
		table_perm = any_perm = true;

	/* Make sure the tuple is fully deconstructed */
	slot_getallattrs(slot);

	for (i = 0; i < tupdesc->natts; i++)
	{
		bool		column_perm = false;
		char	   *val;
		int			vallen;
		Form_pg_attribute att = TupleDescAttr(tupdesc, i);

		/* ignore dropped columns */
		if (att->attisdropped)
			continue;