[Fwd: Re: [GENERAL] Unisersal B-Tree]

Hi J�rg,

I know we have indices and sub-indices, but this also sounds
interesting.

Do you mind if I forward this email to the pgsql-hackers@postgresql.org
mailing list?

Regards and best wishes,

Justin Clift

J�rg Schulz wrote:

Hi Cliff,

I've read an article in the german magazine c't (2001/1 P174) about this
new astonishing method. After I realized that none of the major commercial
databases implement this for now (afaik there is only one database on the
market "Transbase HyperCube" www.transaction.de), I thought it would be a great
chance for an open source database. I even think it's a "must have feature"
in the near future.

But what is it about? It can dramatically speed up queries that run over more
than one index. Think of a query like this:

select a,b,c from table where ( a>min_a and a<max_a ) and ( b>min_b and b<max_b )

In a conventional implementation you have two indexes on attributes a and b.
But to run this query the database engine profits only from one index. It has
to run through all the values of the other. This gets even worse if you use more
constraints, and this scheme is typical for things like OLAP.

With the new methode you add one UB-index that embraces a and b. And you run
only once through this index.

There are a number of papers available under mistral.in.tum.de that explain
the basic concepts.

Regards,

J�rg Schulz

----- Original Message -----
From: "Justin Clift" <justin@postgresql.org>
To: "JXrg Schulz" <jschulz@sgbs.de>
Sent: Sunday, April 29, 2001 6:40 AM
Subject: Re: [GENERAL] Unisersal B-Tree

Hi J�rg,

What advantages do they have?

Regards and best wishes,

Justin Clift

JXrg Schulz wrote:

Are there any plans to implement UB-Trees
multidimensional indexes?

J�rg Schulz

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"My grandfather once told me that there are two kinds of people: those
who work and those who take the credit. He told me to try to be in the
first group; there was less competition there."
- Indira Gandhi