RE: ITL waits

So you have a particular table.  

Let’s talk about that table.  

How many rows are there per block for that table? (min, max, average).  

How many insert, update, and delete operations can reasonably be simultaneously in play for that table?  

I’m restraining myself from asking about indexes because you wrote that you’re sure that is not it.  

Are rows inserted into this table born “full length” or is a skeleton key insert made with lots of null columns which are then updated to actual values?  

Are the rows often multi-block rows?  

Are there many migrated rows?  

After a row is inserted and perhaps updated a few times very soon after the insert, does it tend to become quiet and rarely if ever be updated again?  

Your answers to these questions will tend to reduce the possible improvement suggestions from hundreds to a dozen or fewer.  

Good luck,  

mwf  

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Krishnaprasad Yadav Sent: Thursday, April 04, 2024 1:02 PM
To: Pierre Labrousse
Cc: Oracle L
Subject: Re: ITL waits  

Adding some more info , querys lio is around 15 to 17 only  

On Thu, 4 Apr, 2024, 22:31 Krishnaprasad Yadav, <chrishna0007_at_gmail.com> wrote:

Dear Pierre,  

Thanks for your reply  

I have seen top object is table from reports , so 100%sure on it  

I know inittrans would help but what i feel that its might be cascaded one (suspecting) because as i mentioned

Concurrency is low , table size is low

Not sure about connection strom which i need to work on  

Regards,

Krish    

On Thu, 4 Apr, 2024, 21:43 Pierre Labrousse, <Pierre.Labrousse_at_digora.com> wrote:

Hello Krishna,  

Are you sure that waits are on table segment and not on index segment ? Generally this waits appears more on indexes than tables.  

Effectively, INITRANS should be raised (by default it's 1 for table and 2 for index), but it will be taken into account only for new blocks (unless you move table or rebuild index). You could also raise PCTFREE to have less rows into the same block or create a new tablespace with a data block size smaller to minimize number of rows into the same block and move your tables/index into this tablespace.

Partitioning would be a good solution but it is "just" extra cost 😉  

Best regards.

Pierre             

Pierre LABROUSSE
Consultant DBA ORACLE (OCM 10g/11g/12c)

Mobile +33 (0)7 56 05 27 38

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De : oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> de la part de Krishnaprasad Yadav <chrishna0007_at_gmail.com> Envoyé : jeudi 4 avril 2024 17:05
À : Oracle L <oracle-l_at_freelists.org> Objet : ITL waits  

Dear Gurus ,  

i have made observation of ITL waits in DB , and it lasted more than 4+hrs

i see that certain new DML was introduced newly in database , and same time these ITL wait events triggered .  

I validated top object i see 3 tables were seen as DML are using these tables , i saw concurrency it was around 3k to 10K in 30 mins of snap .

Also table is non partitioned and it was only 3GB in size .  

total execution in DAY was around 400K for all 3 DML statements , seeing these bit surprise that how with such low concurrency its landed in issue

Also able extent management is AUTO .  

i know increasing INITTRANS will help them (probably ?) but i am suspecting its coming something out of DB , i validated OS watcher details , i see some potential bottleneck but those stats which i suspect as bottleneck are seen in good time as well , i validate CPU utilization which was high during start of issue but after 10 mins it got down to 60% but spike remain in DB , validate IO busyness trend is similar to CPU .  

It will be helpful if you can share any of experience from which i can relate and take ahead my case .  

Regards,

Krishna

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