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Message Posted: Fri, 23 Dec 2011 @ 10:57:21 GMT

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Subj:   Re: Calculating uncompressed Size
From:   td newsgroup


interesting task.

Is it right to assume that we talk about multi value compression only?

In case you didn't gather the compression rate at the time of the compression analysis it is not an easy one - at least I guess. And even if you have gathered at point of time actual compression rate might have been changed.

I would follow a bruce force approach. Develop a small application which:

1. collect all tables where MVC is applied.

2. per table

1. show table.

2. create table in a different db (and different name) where you are allowed to do so

3. remove all compress statements from the DDL and create second table

4. Insert / Select sample 1000000 rows from base table and Insert / select into from first into second table - don't forget to place a lock row for access :-)

5. gather space from dbc.allspace and calculate compression rate

6. drop two tables.

you would need a db where you can create the two tables and a user who can select from all DBs - so clearly a DBA task.

And don't run this every day...

This might run some time but impact on system should be very limited.



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