Re: Slow Update

Trying to work out a small set of hints that will work is not trivial, especially when there's not scope for experimenting. However - note that you currently have the following

LEADING(_at_"SEL$AC90CD92" "PO_LINE_LOCATIONS_ALL"_at_"SEL$2" "VW_NSO_1"_at_"SEL$AC90CD92")
USE_HASH(_at_"SEL$AC90CD92" "VW_NSO_1"_at_"SEL$AC90CD92") SWAP_JOIN_INPUTS(_at_"SEL$AC90CD92" "VW_NSO_1"_at_"SEL$AC90CD92")

In particular you've swapped the join inputs and that's why you have a hint that says "when vw_nso_1 is the second table", but the plan LOOKS AS IF vw_nso_1 is the first table. So you need to replace the leading hint, then use_nl() to po_line_locations_all, and get rid of the swap_join_inputs:

LEADING(_at_"SEL$AC90CD92" "VW_NSO_1"_at_"SEL$AC90CD92" "PO_LINE_LOCATIONS_ALL"_at_"SEL$2" )
USE_NL(_at_"SEL$AC90CD92" "PO_LINE_LOCATIONS_ALL"_at_"SEL$2")

These two might work by themselves, but you might find that Oracle decides it's lower cost to stop unnesting, in which case the hint would become invalid.

Regards
Jonathan Lewis

On Fri, 3 Nov 2023 at 15:48, Amit Saroha <eramitsaroha_at_gmail.com> wrote:

> Hi Jonathan,
>
> I am grateful for the insightful comments. I'm going to open an Oracle SR.
> Before closing the thread, if it can be helpful in the interim, could you
> kindly advise on the correct hint to use, as indicated below, which I can
> implement using the SQL_PATCH you previously suggested?
>
> declare
> v1 varchar2(128);
> begin
> v1 := sys.DBMS_SQLDIAG_INTERNAL.I_CREATE_PATCH(
> sql_id => '1fw8tsdwvmg0g',
> name => '1fw8tsdwvmg0g',
> hint_text => '*USE_NL(VW_NSO_1_at_SEL$9C09E64D
> POD_at_UPD$1*)'
> );
> dbms_output.put_line(v1);
> end;
> /
>
> Best Regards,
> AMIT SAROHA
>
>
> On Fri, Nov 3, 2023 at 11:10 AM Jonathan Lewis <jlewisoracle_at_gmail.com>
> wrote:
>
>> Just re-ran the test from the blog note on 23.3, and it's fixed. (Still
>> wrong on 19.11)
>> Fix control 27982637 appeared labelled as 23.1; there's no matching bug
>> or patch visible on MOS, but you could try asking about a backport.
>>
>> Regards
>> Jonathan Lewis
>>
>>
>> On Fri, 3 Nov 2023 at 13:46, Amit Saroha <eramitsaroha_at_gmail.com> wrote:
>>
>>> Hello All,
>>>
>>> I appreciate your input.
>>>
>>> After looking at the statistics, it appears that something is wrong with
>>> them. For example, the PO_RELEASE_ID is inaccurate in a number of the
>>> columns. Additionally, as this is the standard Oracle EBS code for PO line
>>> cancellation, we are unable to alter it.
>>>
>>> I'll gather the stats and try again, but I'd appreciate it if you could
>>> look at the attached file and offer some suggestions if stats have to be
>>> gathered in any specific way. Since it is their standard code, I might also
>>> need to open an Oracle SR. However, this could take some time, and the user
>>> would continue to suffer, so any workaround solution would be very
>>> appreciated.
>>>
>>>
>>> Best Regards,
>>> AMIT
>>>
>>>
>>> On Fri, Nov 3, 2023 at 8:42 AM Jonathan Lewis <jlewisoracle_at_gmail.com>
>>> wrote:
>>>
>>>>
>>>> You're right. And that's why it didn't switch. (Though that's not a
>>>> good enough reason to change the global setting just for this query, of
>>>> course.)
>>>>
>>>>
>>>> I scanned the list three times and still managed to miss it. Now, if it
>>>> had been an underscore !!
>>>>
>>>> Regards
>>>> Jonathan Lewis
>>>>
>>>>
>>>>
>>>> On Fri, 3 Nov 2023 at 11:49, Timur Akhmadeev <timur.akhmadeev_at_gmail.com>
>>>> wrote:
>>>>
>>>>> There's optimizer_adaptive_reporting_only=true which explains lack of
>>>>> adaptive execution. It's not a recommended eBS setting BTW.
>>>>>
>>>>> On Fri, Nov 3, 2023 at 2:38 PM Jonathan Lewis <jlewisoracle_at_gmail.com>
>>>>> wrote:
>>>>>
>>>>>> I didn't say "swap the stats" I said "swap some details of the
>>>>>> stats". It's a fine distinction, but I certainly wouldn't expect Amit to
>>>>>> ask for and import a full metadata export with stats of Jo's table.
>>>>>>
>>>>>> Don't forget that the plan is set by the optimizer's best guess of
>>>>>> what's going to happen at run time, so it's fairly irrelevant that one of
>>>>>> the components of the guesswork didn't execute at all. However, it feels a
>>>>>> little suprising that adaptive execution didn't come into play to switch
>>>>>> the hash join to a nested loop join (it is 19c, after all) when the
>>>>>> vw_nso_1 completed and acquired so little data. (I can't see any place in
>>>>>> the output where we could find out if adaptive execution had been disabled
>>>>>> - I thought it would show in the optimizer environment, but there's no
>>>>>> mention there. Maybe there's a restriction on adaptive execution when
>>>>>> there are "conditional" subqueries in play.)
>>>>>>
>>>>>> Regards
>>>>>> Jonathan Lewis
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Fri, 3 Nov 2023 at 11:13, Timur Akhmadeev <
>>>>>> timur.akhmadeev_at_gmail.com> wrote:
>>>>>>
>>>>>>> I think swapping stats is not a good idea since the data is
>>>>>>> different - things like ORG_ID at least - which will impact estimates with
>>>>>>> different inputs in different DB. Changing num_distinct/num_rows/similar
>>>>>>> things might be OK.
>>>>>>> It's best to gather stats on the table and indexes and see if the
>>>>>>> plan changes - perhaps the index/table stats are not in sync and causing
>>>>>>> this bug.
>>>>>>> Also I find it funny that lines 15-17 are not even executed because
>>>>>>> of the conditional FILTER operation, yet causing misestimates and wrong
>>>>>>> choice of the join method.
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Nov 3, 2023 at 1:02 PM Jonathan Lewis <
>>>>>>> jlewisoracle_at_gmail.com> wrote:
>>>>>>>
>>>>>>>> There are times when I get to feel really smug!
>>>>>>>>
>>>>>>>> Maybe you could swap some details of the stats on that table, its
>>>>>>>> indexes and the column in the critical predicates with Amit to help
>>>>>>>> identify why the silly cardinality estimate has appeared.
>>>>>>>>
>>>>>>>> Regards (and thanks)
>>>>>>>> Jonathan Lewis
>>>>>>>>
>>>>>>>> On Fri, 3 Nov 2023 at 08:23, Holvoet Jo <J.Holvoet_at_dwl.be> wrote:
>>>>>>>>
>>>>>>>>> I can find that exact same sql_id in our Oracle EBS db as well,
>>>>>>>>> and our execution plan is basically doing what Jonathan says : a NL join
>>>>>>>>> between VW_NSO_1 and a unique index scan on PO_LINE_LOCATIONS_U1 instead of
>>>>>>>>> your hash join with a full table scan. We end up with a cost of 6 for the
>>>>>>>>> update and execution times in the centisecond range (although here it is
>>>>>>>>> hardly ever executed – at most once every few days).
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Regards
>>>>>>>>>
>>>>>>>>> Jo
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Regards
>>>>>>> Timur Akhmadeev
>>>>>>>
>>>>>>
>>>>>
>>>>> --
>>>>> Regards
>>>>> Timur Akhmadeev
>>>>>
>>>>

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