I have a client's statspack that shows -

Statistic Total per Second
per Trans
--------------------------------- ------------------ --------------
------------
index fast full scans (full) 6,116 1.7
0.1
index fetch by key 84,919,414 23,595.3
1,920.6
index scans kdiixs1 161,115,221 44,766.7
3,643.8

Any idea what "index scans kdiixs1" is?

My belief (from comparing the top SQL and it's plan) is this is related
to B*Tree to Bitmap conversion, but would be great if anyone knows it
better.

Thanks,

OD

On Oracle 9.2.0.5:

stat# 206 -> Index fetch by key
stat# 207 -> index scans kdiixs1

Index fetch by key:
This stat will be incremented for each "INDEX (UNIQUE SCAN)". This also
applies to all DML statements which has "INDEX(UNIQUE SCAN)" in the
execution plan.

Index scans kdiixs1:
This stat is incremented for each index range scan operation, except
for index fat full scans, index full scan, and index unique scan.

create table t(a number not null, b number);
create index t_idx1 on t(a):
create unique index t_idx2 on t(b);
analyze table t compute statistics;
insert into t select rownum, rownum+50000 from dba_objects;

23:29:56 SQL> select * from v$sesstat where sid=181 and statistic#
between 203 and 207
23:29:56 2 /

SID STATISTIC# VALUE
----- ---------- ----------
181 203 4
181 204 0
181 205 0
181 206 21
181 207 66

23:29:56 SQL> select count(*) from t where a=17;

COUNT(*)
----------
1

23:30:16 SQL> @t
23:30:17 SQL> select * from v$sesstat where sid=181 and statistic#
between 203 and 207
23:30:17 2 /

SID STATISTIC# VALUE
----- ---------- ----------
181 203 4
181 204 0
181 205 0
181 206 21
181 207 67

23:30:17 SQL> select a.a, b.a from t a, t b where a.a=b.a and a.a=100;

A A
---------- ----------
100 100

23:30:24 SQL> @t
23:30:26 SQL> select * from v$sesstat where sid=181 and statistic#
between 203 and 207
23:30:26 2 /

SID STATISTIC# VALUE
----- ---------- ----------
181 203 4
181 204 0
181 205 0
181 206 21
181 207 69

23:30:26 SQL> select a.a, b.a from t a, t b where a.a=b.a and a.a=100;

A A
---------- ----------
100 100

23:30:29 SQL> @t
23:30:31 SQL> select * from v$sesstat where sid=181 and statistic#
between 203 and 207
23:30:31 2 /

SID STATISTIC# VALUE
----- ---------- ----------
181 203 4
181 204 0
181 205 0
181 206 21
181 207 71

Thanks,
Sai.

KDIIXS, KDISPO, KDIFXS, KDIRLS are routines that do a range scan

kdiixs initializes the kdi (Kernel Data layer Index) state for an index
scan