Re: High mbrc in aux_stats$
- From: fairlie rego <fairlie_r@xxxxxxxxx>
- To: Brandon.Allen@xxxxxxxxxxx, oracle-l@xxxxxxxxxxxxx
- Date: Fri, 10 Mar 2006 16:41:55 -0800 (PST)
Hi,
I have seen this generally to be incorrect in 9.2 and I set it manually using
dbms_stats.set_system_stat.
The default value is -1 but that happens when you do not have enough
multiblock reads during your sampling period.
Regards,
Fairlie
"Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx> wrote:
Anybody seen this before?
Oracle 9.2.0.5 on AIX 5.2:
SQL> show parameter db_file_multiblock_read_count
NAME TYPE VALUE
------------------------------------ ----------- -----
db_file_multiblock_read_count integer 16
execute dbms_stats.gather_system_stats('START');
. . . run batch jobs for 8 minutes . . .
execute dbms_stats.gather_system_stats('STOP');
SQL> select * from sys.aux_stats$;
SNAME PNAME PVAL1 PVAL2
------------------------------ ------------------------------ ----------
----------------
SYSSTATS_INFO STATUS COMPLETED
SYSSTATS_INFO DSTART 03-10-2006 14:22
SYSSTATS_INFO DSTOP 03-10-2006 14:30
SYSSTATS_INFO FLAGS 1
SYSSTATS_MAIN SREADTIM 3.864
SYSSTATS_MAIN MREADTIM 10.811
SYSSTATS_MAIN CPUSPEED 546
SYSSTATS_MAIN MBRC 97 <----???
SYSSTATS_MAIN MAXTHR 2957312
SYSSTATS_MAIN SLAVETHR -1
Notice the MBRC figure of 97 even though I have
db_file_multiblock_read_count=16. I searched Metalink for bugs and known issues
but no luck. I guess the next step is to peform a 10046 trace and check the p3
value for all the 'db file scattered reads', but I figured I'd check to see if
any of you have already seen this before I go to that trouble.
Thanks,
Brandon
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