Re: purge of AWR historical tables

Hello

I went through Dominic's article and we are reviewing the entire SYSAUX tables. I will keep you posted about the approach we will follow to fix this issue.

By the way, we discovered this problem during the upgrade process of 12c to a 19c during the DST (Time Zone) check and apply process where it was taking too much time

Best regards
Mohamed

Le ven. 23 avr. 2021 à 13:49, Jonathan Lewis <jlewisoracle_at_gmail.com> a écrit :

>
> I've just found the note I wrote about this "pending = future date" trick;
> https://jonathanlewis.wordpress.com/2018/07/09/historic-stats/
>
> Regards
> Jonathan Lewis
>
>
> On Fri, 23 Apr 2021 at 12:48, Jonathan Lewis <jlewisoracle_at_gmail.com>
> wrote:
>
>> I've just commented on something similar on Dominic's blog note.
>> It's possible that this has something to do with pending or priviate
>> statistics.
>> The last time I looked (possibly in a recent version only) pending stats
>> had a future date.
>> Maybe at some time in the past they were implemented with a date in the
>> far past constructed from the SID and Serial# of the session creatring them
>> - which would explain the SQL reported by Dominic in his blognote.
>>
>>
>> Regards
>> Jonathan Lewis
>>
>>
>>
>> On Fri, 23 Apr 2021 at 12:23, Noveljic Nenad <nenad.noveljic_at_vontobel.com>
>> wrote:
>>
>>> I remembered a similar problem on a 12.1 database from long time ago.
>>>
>>>
>>>
>>> sys.wri$_optstat_tab_history was growing.
>>>
>>>
>>>
>>> I figured out the statistics purging job was executing the following
>>> delete:
>>>
>>>
>>>
>>> DELETE /*+ dynamic_sampling(4) */
>>>
>>> FROM sys.wri$_optstat_tab_history
>>>
>>> WHERE savtime < :1
>>>
>>> AND savtime > TIMESTAMP '1900-01-01 00:00:00 -0:0'
>>>
>>> AND ROWNUM <= NVL ( :2, ROWNUM);
>>>
>>>
>>>
>>> I assume that :1 was systimestamp-retention.
>>>
>>>
>>>
>>> The key point was that the statistics from the 19th century weren’t
>>> considered for deleting.
>>>
>>>
>>>
>>> Statistics for two tables were from long ago:
>>>
>>>
>>>
>>> select table_name,last_analyzed from dba_tables where table_name in
>>>
>>> (select object_name from dba_objects where object_id in
>>>
>>> ( select obj# from sys.tab$ where analyzetime in (select
>>> max(analyzetime) from sys.tab$ where analyzetime is not null ) ));
>>>
>>> TABLE_NAME LAST_ANALYZED
>>>
>>> TAB1 01.01.0001
>>>
>>> TAB2 01.01.0001
>>>
>>>
>>>
>>> These weren’t considered by the delete.
>>>
>>>
>>>
>>> To rule this out, check for strange last_analyzed entries.
>>>
>>>
>>>
>>> I don’t know the origin of these entries. There were already there when
>>> I started the job. I couldn’t find v$database.created in my notes, but
>>> people who have been here longer swear that the database was created in
>>> this century.
>>>
>>>
>>>
>>> I reset the last_analyzed by setting manually setting statistics, which
>>> fixed the problem:
>>>
>>>
>>>
>>> exec dbms_stats.set_table_stats(
>>> OWNNAME=>'K',TABNAME=>'TAB1',NUMROWS=>10000);
>>>
>>> exec dbms_stats.set_table_stats(
>>> OWNNAME=>'K',TABNAME=>'TAB2',NUMROWS=>10000);
>>>
>>>
>>>
>>>
>>>
>>> Best regards,
>>>
>>>
>>>
>>> Nenad
>>>
>>>
>>>
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