In 10g and 11g, dba_hist_seg_stat keeps hourly deltas of v$segment_statistics and you can identify what causes the buffer_busy waits by object each hour.

SQL> @buffer_busy
Object Buffer Busy Waits
———————— —————–
JOB 69
STEP 76
RATIONS_PK 85
CBASE_PROPERTIES1_S 157
STEP_PK 165
JOB_INSTANCE_PK 188
PARTITION_PK 189
STEP_INSTANCE_PK 190
JOB_PK 224
PARTITION_INSTANCE_PK 233
JOB_INSTANCE 248
STEP_INSTANCE 422
PARTITION_INSTANCE 458
G_REGISTRATIONS_PK 508

buffer_busy.sql:
– Must have statistics_level=typical
col “Object” format a30
set numwidth 12
set lines 132
set pages 50
select * from(
select DECODE(GROUPING(a.object_name), 1, ‘All Objects’,
a.object_name) AS “Object”,
sum(case when a.statistic_name = ‘buffer busy waits’
then a.value else null end) “Buffer Busy Waits”,
sum(case when a.statistic_name = ‘physical reads’
then a.value else null end) “Physical_Reads”,
sum(case when a.statistic_name = ‘physical writes’
then a.value else null end) “Physical_writes”,
sum(case when a.statistic_name = ‘logical reads’
then a.value else null end) “Logical Reads”
from v$segment_statistics a
where a.owner like upper(‘%’)
group by rollup(a.object_name)) b
where b.”Buffer Busy Waits”>0
order by 2
/
clear columns
ttitle off

In 10g and 11g the following works great:

SQL> @dba_hist_buffer_busy
BEGIN_INTERVAL_ BUFFER_BUSY NAME
————— ———— ————————–
19-MAR-08 02.00 432 CONTENT.IDX_ECM_CONTENT_ID
19-MAR-08 02.00 247 CONTENT.IDX_ECM_CONTENT_ID
19-MAR-08 09.00 42 SITE.BATCH_STEP_INSTANCE
19-MAR-08 09.00 43 SITE.BATCH_STEP_INSTANCE
19-MAR-08 04.00 1427 SITE.BATCH_JOB_PK

dba_hist_buffer_busy.sql:
set pages 50
column name format a40
set lines 130
column begin_interval_time format a15
set wrap off
select begin_interval_time,BUFFER_BUSY_WAITS_DELTA buffer_busy,
PHYSICAL_WRITES_DELTA writes,
ROW_LOCK_WAITS_DELTA row_locks,
owner||’.'||object_name name
from dba_hist_seg_stat dhss,dba_objects do ,sys.wRM$_SNAPSHOT ws
where begin_interval_time > sysdate-10
and dhss.BUFFER_BUSY_WAITS_DELTA>1
and do.object_id=dhss.obj#
and ws.snap_id=dhss.snap_id
– to find largest order by BUFFER_BUSY_WAITS_DELTA
order by begin_interval_time
/

Have you used it before? What are your thoughts?

I don’t want to eliminate free blocks because I’m looking for contention and would be interested seeing any objects that ever had blocks on the latch chain. However I guess I could get rid of rollback and temp for now… although honestly I should probably outer join them in – but I’ll leave that for a future update. I’m updating the post now!

Also, your link to Lewis’ page led me to a few other great posts so I’ve added them to the bottom of the post. Thanks again!