Comment 2 for bug 721176

Peter,

In 5.5 Rows_read and Rows_sent are always the same simply because the same value is used for both due to a bug in porting slow_extended.

I'm not sure how to demonstrate "always", but here's just one example:

create table t1(a int);
insert into t1 values(1),(2),(3),(4);
set @@min_examined_row_limit=1;

select * from t1;
# Query_time: 0.000413 Lock_time: 0.000152 Rows_sent: 4 Rows_examined: 4 Rows_affected: 0 Rows_read: 4
select * from t1 where a=1;
# Query_time: 0.000607 Lock_time: 0.000299 Rows_sent: 1 Rows_examined: 4 Rows_affected: 0 Rows_read: 1
select * from t1 where a=5;
# Query_time: 0.000460 Lock_time: 0.000170 Rows_sent: 0 Rows_examined: 4 Rows_affected: 0 Rows_read: 0

Which raises 2 questions:

1. Why is Rows_read different in all three cases?
2. What is Rows_read really supposed to mean?