Re: OT: Misinformation Ranting

From: Thomas Day <tday6_at_csc.com>
Date: Tue, 10 Sep 2002 16:41:58 -0400
Message-Id: <22528.293392@fatcity.com>

<sympathy>

I can't tell you how many times I've tried to explain to more junior DBAs that number of extents doesn't matter anymore.

Then they'll point me to some official looking book where it says, "They do too matter."

What's embarrassing is that for a time part of being a good DBA was figuring out your INITIAL and NEXT so that you got only 1 or 2 extents per table or index. But that whole issue is now so 2nd millennium.

</sympathy>

                                                                                                                   
                    Jared.Still                                                                                    
                    @radisys.com         To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>       
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                                         Subject:     OT:  Misinformation Ranting                                  
                                                                                                                   
                    09/10/2002                                                                                     
                    04:28 PM                                                                                       
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                    ORACLE-L

<RANT>

I've just spent 30 minutes with our SAP administrator trying to convince her that we really don't need to reorganize the tables in our production SAP database.

Due to some misinformation in an Oracle Press book, 'Oracle Unleashed' I think, she is equating number of extents with fragmentation.

The text she referred me to is in fact discussing 'migrated rows' though that term is never used. She has become convinced that if the extents allocated for tables are not all in contigous space, some very nasty fragmentation will occur.

I tried taking it down to disk and explaining that an OLTP system with hundreds of users won't really see much benefit from this, but she wasn't really ready for that. :)

Her concern is that there are 29000 extents in an index tablespace. This might have something to do with there being 3400 indexes in said tablespace.

Total 'wasted' ( honeycomb ) space in this 250 gig DB is < 20 meg. Not much to gain there.

The text of the book states that you should expect a '10 to 20 percent performance increase' by reorganizing the tables/indexes. No data to back it up of course.

This is on a database that performs very well most of the time, outside of a couple of custom reports that run too long. No complaints from users about slowness.

Arrghhh!

I just had to vent to the list, cuz there's no one here that understands.

<\RANT>

Jared

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Received on Tue Sep 10 2002 - 15:41:58 CDT