1) Are queries at the sensor level, or do you need to aggregate data across all sensors? If the latter, then it's hair-pulling to have them in separate tables.
2) If all data are in one table, performance should not be an issue for an "industrial strength" database like DB2, Oracle, SQL Server, etc., but almost certainly will be an issue for Paradox and its ilk. Properly structuring the primary key will help a lot, check with your DBA for the best key structure given your expected Selects. (Or if you're the DBA, the manuals give tips and hints for that sort of stuff.) 3) If snappy access to individual sensors is important, and also selecting across all sensors is important, you could keep the data in separate tables, then run a nightly Update (or, more like 5 to 100 Updates!) to copy today's data from the 100 individual tables into a central table. Then you can query the central table [aka data warehouse] for data across all sensors. At 12:29 AM 6/11/2008, Chris Stebbing wrote: >Hi All, > >I have a question on database design if I may. The application that >I will be working on is an industrial one where we will be logging >data from a number of different sensors all at differing rates. The >"current" data value is used to initiate actions and is always held >in memory, but past data is most commonly graphed regularly. By far >the largest amount of data is generated by logging these sensors, >and the most common use for this data is simply graphing. > >An installation could range anywhere from 5 sensors to 100 sensors. > >The main question I have is whether it would be better to have all >these sensors log into one table, or have them log into a separate >table per sensor. The amount of data can build up quite an amount >over time, and filtering one large table (or querying one large >table) takes an amount of time. Having the data already separated >by sensor would be a huge head start. > >Thanks for any comments and my apologies if this question is out of line here. > >Regards, >Chris. > > > >_______________________________________________ >Delphi-DB mailing list >Delphi-DB@elists.org >http://lists.elists.org/cgi-bin/mailman/listinfo/delphi-db Regards, Sid Gudes PIA Systems Corporation [EMAIL PROTECTED] _______________________________________________ Delphi-DB mailing list Delphi-DB@elists.org http://lists.elists.org/cgi-bin/mailman/listinfo/delphi-db
