Re: how many LIOs is too many

From: Chris Taylor <christopherdtaylor1994_at_gmail.com>
Date: Mon, 20 Jan 2014 19:54:25 -0600
Message-Id: <86228BDF-173D-4172-886B-BB24D15CF7D5_at_gmail.com>

That query seems suspect at best. I would track down someone at your org that knows about it and question its validity as its chewing up cpu cycles and you need to understand the business need for the query and what it is doing.

Sent from my iPhone

> On Jan 20, 2014, at 5:31 PM, Ram Raman <veeeraman_at_gmail.com> wrote:
>
> List,
>
> We have a SQL that is being executed few thousand times in an hour. The SQL belongs to an application supplied by a 3rd party vendor. The SQL accesses 500 rows from a million row table every time it executes, using idx range scan. This is spiking up the resource usage consistently. (Do not know why an application would need 500 rows constantly, it uses rownum to filter out top 500 rows after order by asc).
>
> As of now this is the stats:
>
> SQL_ID FETCHES EXECUTIONS DISK_READS BUFFER_GETS CPU_SEC ELAPSEDSEC FIRST_LOAD_TIME
> ------------- ---------- ---------- ---------- ----------- ---------- ---------- -----------------------
> 037xx0tb72t5r 789387 789388 80 1998534791 1719853.25 1820107.77 2013-12-18/08:06:26
>
> The LIO per exec was at ~1600 yesterday, it has gone to 2500 today.
>
> I have couple of questions
>
> 1) Has anyone in this list worked on an app that does repeated executions of a sql retrieving so many rows.
> 2) Is there any formula to calculate the number of LIOs for a SQL when it is time to say the sql is doing too many LIOs per exec.
>
> v11.2
> TIA,
> Ram.
>

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Received on Tue Jan 21 2014 - 02:54:25 CET