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Re: Large table optimization
Posted by: Viorel Serbu
Date: December 29, 2009 10:45AM

Indeed w/o "group by" the query time is significant lower and its not "quite" mandatory since it might be moved on the application side. But still the query time is too high (around 5 sec for 10 mils records wo avg, vs 15 sec with avg).
At this moment i added an index on systime which made an "avg" query to last 3 sec and a "non avg" query to last less than 1 sec.
The system works at this time but with only 3 channels out of 20. No buffers overrun which for me means that the db inserts can keep the pace with the sampling rate for the current number of the records (10 mils) in the table. I'll wait to see what happens when i'll add 5 more channels in early jan.

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