Re: ASSM and tablespace fragmentation in a table that adds 140,140
Date: Sat, 04 May 2013 12:20:32 +0200
Message-ID: <5184E0F0.1030604_at_www.sqltools-plusplus.org>
> Since ASSM uses different size extents, are there any issues with
> fragmentation? There was an Oracle-L thread dating from 2007 that discussed
> this.
You have to be very careful with all these acronyms - ASSM is about how the blocks are managed within an extent (MSSM freelist based vs. ASSM), so this is probably less relevant to what you're actually looking for.
You seem to think more in terms of System Managed Extent sizes (also known as AUTOALLOCATE) vs. UNIFORM extent size for Locally Managed Tablespaces.
You can have all kinds of combinations: AUTOALLOCATE with MSSM, UNIFORM with ASSM, etc., however depending on the features you want to use (Bigfile Tablespaces, Securefiles), in general the newer the features, they are no longer supported with MSSM.
To address your question: System Managed Extents can be subject to fragmentation - recently I got to know that the AU size adds another twist to the allocation algorithm - I've posted about that here:
http://oracle-randolf.blogspot.de/2013/04/asm-au-size-and-lmt-autoallocate.html
Randolf
-- http://www.freelists.org/webpage/oracle-lReceived on Sat May 04 2013 - 12:20:32 CEST