Re: Named Mistakes and Questionable Practices
Date: 13 Jun 2006 08:13:20 -0700
Not really; OTLT is all the encoding schemes shoved into a single non-table (by definition a table is a set of one kind of thing). EAV is an attempt to "rubberize" the entire schema so it can change on the fly.
But they both involve mixing data and meta-data in a schema! Sounds like a start for that taxonomy ..
>> Integrity in the Apps <<
There is a long thread with someone trying to defend that one
>> [Denormalized tables] I'll materialize a view which turns out to be a denormalized table especially when the view does something heavy and doesn't have to be all that fresh. <<
Sounds like you are talking about a data warehouse and not OLTP. I have no trouble with Star and Snowflake schemas, since the data is frozen and the sources were normalized. Probably should have said OLTP base tables. Denormalized VIEWs in an OLTP are suspect, tho; you cannot update them or trust their information.
My favorite is a VIEW that hides a CROSS JOIN, so the aggregates are garbage.
>> [Auto-increment methods for keys] Do you mean "clever" ways to autogenerate keys, or using autogenerated keys at all, or...? <<
Any at all. They are not keys by definition; a key has to be a subset of the attributes of the entity and not the internal state of a counter or other device in the hardware that stores the data. For Oracle people (and others), they can actually get the physical location as a track/sector addrress and put it in code. Very fast access, but fatal after a disk re-organization.
The taxonomy class could be mixing physical and logical data ...
>> [No keys at all] I can't say I've seen this recently. <<
All the time! Just Google a newsgroup for anyone asking about removing duplicates from a "table" and 7 times out of 10, they had an auto-increment and 3 out of 10, they had nothing at all (it was supposed to be a temp table -- read: scratch tape, like we used to use on early file systems mimiced in SQL)
I had forgotten that one! Received on Tue Jun 13 2006 - 17:13:20 CEST