Re: ODS and Star-Query
On 10 Feb 1998 14:20:54 GMT, "Christoph Kuenzle" <christoph.kuenzle@adi.ch> wrote: >We are planning to build a data warehouse with Informix Online Dynamic >Server 7.24 using extended parallel option and advanced decision support >option. I am not so sure you can combine these. Check with your sales rep. >Three Questions: > 1. Does Informix ODS 7.2x support star queries? Well, every relational database "supports" star queries, so I assume your question is wether they have some special indexing or other performance enhancments for them. Some 2 years ago they said you didn't realy need them. The XPS (now extended parallel option) would do it as fast as anything else via it's parallellism. Last summer at the user conference they talked a lot about several new types of indexes that would be introduced to support start queries. They said they where working on advanced bit map indexing (there are vast differences in the implementation of this), "standard" indexes where even the second or later part of that index could be used for selection, multi table indexes and some others I no longer remember. I don't know if these are implemented yet. The index type that can be used to scan along any part of the index (any column included in it) should be particularly usefull in at least some start queries. They also have the Metacube product family that you should look into of course. See below. > 2. What problems do I have to expect running star queries, > except from full table scans, > which are inevitable in a DWH environment, as I learned. I don't know. I have no experience yet. I am just studying the field to possibly implement such a database. > 3. Are we the only ones trying to run star queries with Informix ODS? You sure are not. There are many others doing this. Additionally a major part of the reason for the Metacube product from Informix is to support star queries (and snowflakes as well as I understand it). They aquired the Stanford Development Group some years ago at a time when they where seen by the OLAP community as having one of the most interesting and best products for ROLAP use. They have developed it since, and just announced another new version (4.0) which got some rave reviews. See http://www.informix.com/cyb-cgi/Webdriver?MIval=cyberzine_view_Story&ID=1212 for the announcement and http://www.informix.com/informix/products/new_plo/metabro/metahm.htm for more detailed information. Data warehouse solutions is one of the realy strong points of Informix and their products. > >Thanks >-- >Christoph Kuenzle >ATAG debis Informatik AG >4900 Langenthal >Switzerland > Nils Myklebust NM Data AS Norway E-mail: Nils.Myklebust@nmdata.com