Re: Is this De-Normalization?
Date: Mon, 1 Dec 2003 11:39:27 -0800
"tom dorgan" <tdorgan_at_yahoo.com> wrote in message <news:d4518ef4.0312011036.311b9a1a_at_posting.google.com>...
> We have a table, call it DataParent. Another table, call it
> DataChildren, contains foreign keys to DataParent. You get the idea
> that this is a one-to-many relationship like the well-known Order and
> LineItem pair.
> In a discussion regarding increasing performance, the idea was brought
> up to pull each of the DataChildren items into the DataParent table by
> using a fixed number of columns, call them DataChildren1-N in
> DataParent. Leave unused slots null and only allow N DataChildren per
This way madness lies. Will these DataChildren1-N hold keys for rows in DataChildren, or is DataChildren going away entirely?
> I understand this to be First Order de-normalization - we are putting
> an array, set or tuple into a table. I was told that this was not the
> case but did not get an explanation.
I've heard of one case where something similar /may/ be justified, an items-for-sale table with a child table holding price histories. The /current/ price was copied, not moved, into the parent table, with triggers to keep the copy synchronized with the price history.
-- Joe Foster <mailto:jlfoster%40znet.com> "Regged" again? <http://www.xenu.net/> WARNING: I cannot be held responsible for the above They're coming to because my cats have apparently learned to type. take me away, ha ha!Received on Mon Dec 01 2003 - 20:39:27 CET