 |
 |
Archives of the TeradataForum
Message Posted: Wed, 21 Mar 2001 @ 09:16:29 GMT
| Subj: | | Re: Placement of VARCHAR and COMPRESSed Columns In A Row |
| |
| From: | | Dave Sedgwick |
David,
We have compress on many of our fact columns, for example on 40 columns of our 56 column main order table. This came out of
experiments for performance on a very large but sparsley populated main fact table used for a Business Objects development. Whilst
there is a minor overhead to populate the table, we found a big improvement in space saving and also in query performance. I
understand that this is because more data is brought into each (64k?) read block as the compressed values are much smaller. This
only works if you have a value that is very common in the column in question. In our case as it is a sparsley populated dimension
table where zero is very common.
Dave
| |
