I almost always like to have a single column DB generated primary key... Seems to make things easier down the track... could still have a secondary index on the fields mentioned if that would aid performance.
I don't know your application, but how "fine" are the time stamps generated from the system, is there even the remotest possibility that two events could occur on the same sensor at the same time in terms of the resolution of the equipment measuring the time (seconds, milliseconds?)? Even if not, I would probably still have another DB generated primary key column as mentioned above. Just another 2 cents worth. Regards Colin On 12/06/2008, at 11:42 PM, Chris Stebbing wrote: > At 06:03 PM 12/06/08, Marcin Bury wrote: > >> Chris >> >> The answer is ONE table - perfomance is the matter of proper >> indexes... >> >> I would recommend create compund primary key for this table - >> SENSOR_ID, >> UNIQUE_COLUMN > > Hi Marcin, > > thanks for your response. The current primary key is timestamp, > sensor_id but sensorid, timestamp would work just as well and may > prove a little better I suspect. > > Cheers, > Chris. > > _______________________________________________ > Delphi-DB mailing list > Delphi-DB@elists.org > http://lists.elists.org/cgi-bin/mailman/listinfo/delphi-db ##################################################################################### Attention: The information in this email and in any attachments is confidential. If you are not the intended recipient then please do not distribute, copy or use this information. Please notify us immediately by return email and then delete the message from your computer. Any views or opinions presented are solely those of the author. #################################################################################### _______________________________________________ Delphi-DB mailing list Delphi-DB@elists.org http://lists.elists.org/cgi-bin/mailman/listinfo/delphi-db
