Re: SMON - Does it cause a degrade?

From: <Jared.Still_at_radisys.com>
Date: Fri, 25 Jan 2002 15:48:50 -0800
Message-ID: <F001.003FBEDB.20020125155124@fatcity.com>

Since SMON will coalesce anyway if needed when a request for extents is made, what's the point in setting PCTFREE to a value >0 to force periodic coalesces?

An explanation of what takes place during a request for extents is in the concepts manual.

Jared

Rajesh.Rao_at_chase.com
Sent by: root_at_fatcity.com
01/25/02 01:50 PM
Please respond to ORACLE-L

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        Subject:        SMON - Does it cause a degrade?

Hey Fellas,

I have an application DBA who insists that the pctincrease at the data tablespace should be set to 0 so that SMON does not coalesce the tablespace. He says coalesce will be performed by using a scheduled batch job written for that purpose. He states that having SMON to perform an coalesce of the tablespace could cause an performance degrade??? I have never heard of such a thing, but then I dont wanna argue with him. He's got
wrinkles on his face, and grey hair ;-)

My argument would be, go back to the drawing board, get your tables sized properly, if you anticipate fragmentation. And SMON does not cause a performance degrade? It wakes up every 5 minutes, does hold ST enqueue locks if a tablespace needs coalescing, but it does not cause a performance
degrade? Or does it???

Now, can I have a definitive word on this? Any sites, white papers, to refer to that says so, or to the contrary. I need to convince the higher ups.

Raj

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