Re: Sequnce Cache Size in RAC

Dear Experts ,

Thanks for reverting back and clearing the doubts . As per Andy such issue are mostly in No order sequence , so if sequence are ordered so this problem wont be their ,Is my understanding is correct?

Regards,
Krishna

On Wed, 16 Feb 2022 at 12:08, Jon Crisler <joncrisler_at_gmail.com> wrote:

> It is generally a good performance boost to increase the cache size in RAC
> or Exa, but as Andy mentioned you need to make sure your application is
> tolerant of skipped values. This can sometimes be a problem if a RAC node
> crashes and the next value is not propagated. In earlier versions of RAC
> it was a bit hard to chase down performance issues due to non-cached
> sequences, but more recent versions make it easier to track down.
>
> On Wed, Feb 16, 2022 at 1:04 AM Andy Sayer <andysayer_at_gmail.com> wrote:
>
>> This is how a (default) no order sequence behaves. Eg if you set cache
>> size 5 and had two nodes the following sequence values could be chosen in
>> chronological order with uneven distribution of requests:
>> Node 1: 1 (gets 1-5)
>> Node 2: 6 (gets 6–10)
>> Node 1: 2
>> Node 1: 3
>> Node 1: 4
>> Node 1: 5
>> Node 1: 11 (gets 11-15)
>> Node 2: 7
>>
>> Is this a problem? Shouldn’t be. But if your application has a baked in
>> assumption that sequence value is the same as order of insert then there
>> can be logic that no longer works.
>>
>> Thanks,
>> Andy
>>
>> On Wed, 16 Feb 2022 at 04:55, Krishnaprasad Yadav <chrishna0007_at_gmail.com>
>> wrote:
>>
>>> Hi Experts,
>>> Intention to raise this question was , some of my
>>> colleagues suggested that increase in cache size from 0 to bigger number
>>> can cause difference in cache value from both node .
>>>
>>> like in my case , cache size is 0 , and this is RAC environment , so in
>>> this case , certain numbers are cached in node 1 and a separate set will be
>>> cached for node 2 .
>>>
>>> so any maily insert using this sequence can cause issue of difference in
>>> number
>>>
>>> Please share some light on this .
>>>
>>> Regards,
>>> Krishna
>>>
>>>
>>> On Tue, 15 Feb 2022 at 16:45, Laurentiu Oprea <
>>> laurentiu.oprea06_at_gmail.com> wrote:
>>>
>>>> Hello Krishna,
>>>>
>>>> Your question is really incomplete, thus the answers you are getting
>>>> are in consequence.
>>>>
>>>> You might need to provide details on:
>>>> -> why the cache was initially set to 0
>>>> -> what drives the motivation to increase the cache and what kind of
>>>> investigations was undertaken to conclude that the issues will be solved by
>>>> this
>>>> -> what version your database is running
>>>>
>>>> You might want to read these articles by Jonathan Lewis:
>>>> https://jonathanlewis.wordpress.com/2022/02/07/sequence-catalogue/
>>>> and also this article maybe:
>>>> https://oracle-base.com/articles/18c/scalable-sequences-18c
>>>>
>>>> Thanks.
>>>>
>>>> PS: to answer your specific question: increasing cache size for
>>>> sequences in your environment may or may not create issues.
>>>>
>>>> În mar., 15 feb. 2022 la 12:31, Krishnaprasad Yadav <
>>>> chrishna0007_at_gmail.com> a scris:
>>>>
>>>>> Hi Experts ,
>>>>>
>>>>> We are proactively trying to increase sequence cache size , currently
>>>>> the database is in RAC .
>>>>> I need to know if there is a RAC environment , increase in CACHE size
>>>>> of sequence makes any difference . Currently the value is cache_size is 0
>>>>> Does changing value from 0 to 50 of cache_size can cause any issue
>>>>> w.r.t to application .
>>>>>
>>>>>
>>>>> Regards,
>>>>> Krishna
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>

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