Re: slower fetch speed with oracle client 19c vs 11g

Thank you very much Jonathan, SorryI forgot to mention the DB, was not touched recently and is version 19c.

I will try to create a simple test case and set 10046 trace to see the exact wait events. .Good hint about sessions stats I will check this also,

În mar., 21 feb. 2023 la 13:08, Jonathan Lewis <jlewisoracle_at_gmail.com> a scris:

>
> The fetch size might be the same, which would make the number of SQL*Net
> round-trips the same, but are the setting for the SDU (session data unit)
> the same. Extra time might mean a smaller SDU size on the 19c setup. If you
> can't check it directly then check to see if the number of "sql*net MORE
> DATA to client" waits is larger for 19c than it is for 11g.
>
> Another possible cause for the difference in time could be something to do
> with character set translation. If the 11g client and 11g server are using
> the same character set then there's no time spent in SQL*Net on
> translation, but if (somehow) the 19c installation has managed to introduce
> a change in characterset then SQL*Net could be using CPU on the
> translation. You might see this as a change in the statistics relating to
> "bytes sent/received via SQL*net" - but you might have to create a custom
> test to be able to see/measure it (it might also be another cause of
> increases in "more data" waits
>
>
> Regards
> Jonathan Lewis
>
>
> On Tue, 21 Feb 2023 at 10:46, Laurentiu Oprea <laurentiu.oprea06_at_gmail.com>
> wrote:
>
>> Dear colleagues,
>>
>> It started like a performance investigation where DB was blamed that
>> after an application upgrade queries started to be slower. We managed to
>> isolate the issue to only the oracle client.
>>
>> They are using an application (qlikview) using OLEdb for oracle driver.
>> When they configure it with the oracle client 19c is fetching almost 50%
>> slower compared with the 11g client. Everything is identical in rest. I saw
>> from the sql monitor report that the same fetch size is used, probably this
>> is dictated by the driver which is the same in both cases.
>>
>> Anyone have any idea what could be the issue here?
>>
>> Appreciate your help,
>> Laurentiu.
>>
>

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