Re: ASSM worth it?

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Thu, 18 Dec 2003 22:53:35 -0000
Message-ID: <brtb5h$3ag$1$8302bc10@news.demon.co.uk>

I wouldn't bother at present - the concept is quite nice, but there are still (9.2.0.4) a few nasty implementation features (bugs even) in ASSM which can have serious side-effects on space management or performance.

(See http://www.jlcomp.demon.co.uk/bustbits.html for a particularly amusing example - still fails in 9.2.0.4 but fixed in 10.1).

If you execute very large numbers of small insert statements with a high degree of concurrency, then ASSM could cause significant latching problems.

If you currently set PCTFREE to anything in excess of 75 (which would be a little unusual, notwithstanding the comment in the article referenced by Geomancer) then you it is possible to get severely burned on space wastage on deletes.

-- 
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Jonathan Lewis
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"TomT" <dontspam_at_spam.com> wrote in message
news:7P0Eb.24$Nk4.25847_at_news.uswest.net...


> We are getting ready to upgrade from 8i to 9i.  Since we have over 300GB,

> there may be no time to do an export/import; therefore, we are considering

> using the migration tool to upgrade in place.  If we do the upgrade in

> place, we will not get the 9i enhancement ASSM (auto segment space

> management).  Any thoughts on the downside of this?  Thanks.

>

>

Received on Thu Dec 18 2003 - 16:53:35 CST