RE: v$session_longops

Hi,

The session longops array is split into multiple parts each having its own freelist and latch.

Operations on each array are protected by separate "longop free list parent" latches ( controlled by _num_longop_child_latches parameter ).

The max number of longop slots is "hardcoded" into Oracle using ksulomx_ variable:

SQL> oradebug dumpvar sga ksulomx_
ub4 ksulomx_ [380007E78, 380007E7C) = 000001F4 <<<--- 0x1F4 is 500 in decimal

The longop array used by a session is probably determined by a MOD function on SID or Oracle PID, so a session does not see all free slots, thus the "oldest" longop slot doesn't necessarily get reused first.

--
Regards,
Tanel Poder
http://blog.tanelpoder.com
 



> -----Original Message-----

> From: oracle-l-bounce_at_freelists.org 

> [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Gints Plivna

> Sent: Wednesday, October 03, 2007 15:09

> To: info_at_go-faster.co.uk

> Cc: oracle-l_at_freelists.org

> Subject: Re: v$session_longops

> 

> Jonathan Lewis has written an answer here about the maximum 

> number of entries:

> http://www.mcse.ms/message1574958.html

> He said "The number of slots

> in v$session_longops for 9.2.0.6 seems to be the lower of 500 

> and 2 x the sessions parameter."

> Of course you can quite easily test whether it is relevant 

> also for 10g for example.

> 

> However I cannot say anything about the precise algorithm of 

> reuse of entries.


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