Observation 1: Group by (in my case) is faster w/out using the index
than with using the index by 10X
In my app I have a table-
create table foo(k1integer ,k2 integer,k3 integer,...);
create index foo_idx on foo(k1,k2,k3);
when I do-
select k1,k2,sum() as s,count(1) as c from foo group by k1,k2;
The query is 10X slower with the above index created as when I drop
the index and don't use it. Bug or
just happens to be the case for some data distribution this is just
the way it is? Yes, I know I have
a 3 column index and only using 2 for this query.
Observation 2: I can force the index to not be used with '+' but the
result has nulls for key values!
If I do -
select k1,k2,sum() as s,count(1) as c from foo group by +k1,+k2;
then the index is not used, it is fast BUT the output has null values
for k1,k2! Seems like a bug
Thoughts?
-Russ
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