Re: Convert SAP Oracle Database to IBM DB2 Database??
From: DA Morgan <damorgan_at_psoug.org>
Date: Fri, 08 Feb 2008 07:17:26 -0800
Message-ID: <1202483818.714015@bubbleator.drizzle.com>
>
> Eaton's blog is basically correct. However he mentions the negatives of
> the Oracle design, and does not mention the advantages. The greatest
> advantage of having the symbol table local to the page is that you do
> not have to do another I/O to read the symbol table - the single block
> I/O gets the compressed data and the symbols required to uncompress it.
> Our testing in large scale environments shows that to me more beneficial
> than the IBM design. There are also additional benefits accrued from not
> having to expand a single symbol table when the data values grow, etc.
>
> So it's horses for courses. We just think our horses are better. YMMV,
> and as always, test well.
Date: Fri, 08 Feb 2008 07:17:26 -0800
Message-ID: <1202483818.714015@bubbleator.drizzle.com>
Mark Townsend wrote:
>
>>> >>> What I'm saying is that it is not just superficial ... from a >>> technical point-of-view it is mostly incorrect. He needs to learn how >>> to read the >>> on-line docs. >> Well the nice thing about BLOGs is the ability to give feedback. >> You are a teacher, no? Teach! >> >> Cheers >> Serge
>
> Eaton's blog is basically correct. However he mentions the negatives of
> the Oracle design, and does not mention the advantages. The greatest
> advantage of having the symbol table local to the page is that you do
> not have to do another I/O to read the symbol table - the single block
> I/O gets the compressed data and the symbols required to uncompress it.
> Our testing in large scale environments shows that to me more beneficial
> than the IBM design. There are also additional benefits accrued from not
> having to expand a single symbol table when the data values grow, etc.
>
> So it's horses for courses. We just think our horses are better. YMMV,
> and as always, test well.
I disagree Mark ... unless I know something I'm not supposed to talk about (so I won't). Yes the symbol table is on a single-block basis. But the critical information missing from Eaton's blog is the method used to keep compression from affecting insert performance. And of course no mention of compressed tablespaces, no mention of compression without direct path loading, no mention of deduplication, no mention of compressed indexes, etc.
-- Daniel A. Morgan Oracle Ace Director & Instructor University of Washington damorgan_at_x.washington.edu (replace x with u to respond) Puget Sound Oracle Users Group www.psoug.orgReceived on Fri Feb 08 2008 - 09:17:26 CST