Re: Convert SAP Oracle Database to IBM DB2 Database??

From: Mark Townsend <>
Date: Fri, 08 Feb 2008 20:43:54 -0800
Message-ID: <>

> The compression dictionary is part of the table's meta-data, thus it is cached.

At some stage this is going to hit a memory limit, as more data and more tables are compressed.

 > If data values are highly localized, then having local
> dictionaries can be helpful.

That IS the crux of the matter. We think most data is indeed localized, I would be surprised, and willing to discuss over a beer, if IBM thought differently.

BTW - that is why random data generation does not show compression of well in Oracle.

>> No matter how you do it, to get back to the original point of the
>> thread, it is a lousy reason to consider changing the back-end from
>> product A to product B given what I've seen of both.

> I don't think it is a lousy reason. It is an insufficient reason in isolation.

And interesting enough, the whole conversation has been largely irrelevant. The real question to ask - given product A and product B, under SAP, which database takes more space to store the same amount of data ? Firstly uncompressed, and then compressed. The answer is freely available to anyone with a SAP support contract.

Remember that necessity is often the mother of invention, and what is a feature in one product is often a bug/design fix in another. Received on Fri Feb 08 2008 - 22:43:54 CST

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