Re: 12.1.0.2 ADG Reading 1 block at a time? (TEMP / V$SORT_Segment)

Ah. Now I see the block# incrementing by one. (Thank you, Keith Moore, for spotting that.)

Cary Millsap
Method R Corporation
Author of *Optimizing Oracle Performance <http://amzn.to/OM0q75>* and *The Method R Guide to Mastering Oracle Trace Data, 3rd edition <https://amzn.to/2IhhCG6+-+Millsap+2019.+Mastering+Oracle+Trace+Data+3ed>*

On Wed, Jan 22, 2020 at 8:41 AM Cary Millsap <cary.millsap_at_method-r.com> wrote:

> Hi Chris,
>
> What in your trace file is giving you the idea that the process is doing
> 1-block reads?
>
>
> Cary Millsap
> Method R Corporation
> Author of *Optimizing Oracle Performance <http://amzn.to/OM0q75>*
> and *The Method R Guide to Mastering Oracle Trace Data, 3rd edition
> <https://amzn.to/2IhhCG6+-+Millsap+2019.+Mastering+Oracle+Trace+Data+3ed>*
>
>
>
> On Tue, Jan 21, 2020 at 6:01 PM Chris Taylor <
> christopherdtaylor1994_at_gmail.com> wrote:
>
>> So we use an ADG standby db for reporting and we've got some problem SQLs
>> that I'm putzing around with because they work fine in all our other
>> non-standby databases.
>>
>> Looking deeper into the tracefile, I see it doing 1 block at a time reads
>> , even though it says its reading 128.
>>
>> It does this on both of our ADG Standby Databases which are on completely
>> different hardware.
>>
>> WAIT #140196872952648: nam='db file scattered read' ela= 1588 file#=4097
>> block#=579715946 blocks=128 obj#=-39778567 tim=17263910670242
>> WAIT #140196872952648: nam='db file scattered read' ela= 1495 file#=4097
>> block#=579715947 blocks=128 obj#=-39778567 tim=17263910672065
>> WAIT #140196872952648: nam='db file scattered read' ela= 1671 file#=4097
>> block#=579715948 blocks=128 obj#=-39778567 tim=17263910674042
>> WAIT #140196872952648: nam='db file scattered read' ela= 1094 file#=4097
>> block#=579715949 blocks=128 obj#=-39778567 tim=17263910675443
>>
>> File# in this case is the TEMP Segment from V$SORT_SEGMENT.
>>
>> If I check V$SORT_SEGMENT, I don't see any object that has that many
>> blocks.
>>
>> I'm considering dropping & recreating the TEMPFILE in the two standby
>> databases to see if that will resolve the issue.
>>
>> Anyone seen anything like that before?
>>
>> Chris
>>
>>

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