Re: select for update wait issues

EVENT                                        ROW_CNT
----------------------------------- ----------------
db file sequential read                        7,714
enq: PR - contention                             551
latch free                                    11,020
log file sync                                 96,425
read by other session                          7,163

On Mon, Apr 13, 2015 at 10:53 AM, Mladen Gogala <dmarc-noreply_at_freelists.org
> wrote:

> On 04/13/2015 12:25 PM, Sandra Becker wrote:
>
>> Oracle 11.2.0.2
>> Solaris 10 64-bit on Oracle T5
>> EMC storage (fast cache enabled)
>>
>> Last Wednesday night we moved a production database to new hardware. We
>> do not have the option to move it back. On Friday we started experiencing
>> severe performance issues. ASH reports show the "SELECT...FOR UPDATE
>> WAIT..." running as the top SQL for events and row sources. This is NOT
>> new code. What can I look at, is there anything I can do, short of killilng
>> sessions, to get this under control? I'm opening a ticket with Oracle, but
>> this forum generally responds faster.
>>
>> I'm not really familiar with how the SELECT FOR UPDATE WAIT works and
>> haven't found a good explanation yet. The select is on a partitioned
>> table. Does it lock only a row or does it lock the partition? At times I
>> can see a dozen or more of these statements running. Once they complete, I
>> then see a lot of waits on log file sync.
>>
>> If anyone knows, how does having fast-cache enabled affect this?
>>
>> Thanks for any suggestions/guidance.
>>
>> --
>> Sandy
>> GHX
>>
>
>
> Hi Sandra,
> What event exactly are your sessions waiting on?
> Regards,
>
> --
> Mladen Gogala
> Oracle DBA
> http://mgogala.freehostia.com
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

-- 
Sandy
GHX

--
http://www.freelists.org/webpage/oracle-l