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8.6

Query optimization: Aggregation over months - 14 million records

Asked by risoy in MS SQL Server

Tags: aggregation, month, optimization

I need to be able to report the speed of a machine that is operating 24/7 and see how it changes over time. I have in tblProdhist the speed recorded every second.

The output should be like this:

Period       AvgSpeed
2005-1      516.09
2005-2      311.98
2005-3      498.12

The query is dynamically created depending on the year that is specified, the months that are specified, days etc. The below example uses year 2005 and january, february and march.

SELECT CAST(Year(LogTime) AS varchar) + '-' + CAST(Month(LogTime) AS varchar) As Period, AVG(MillVelocityActual) AS AvgSpeed
FROM tblProdhist
WHERE 1=1 AND Year(LogTime) IN (2005) AND Month(StartTime) IN (1,2,3)
GROUP BY CAST(Year(LogTime) AS varchar) + '-' + CAST(Month(LogTime) AS varchar)
ORDER BY CAST(Year(LogTime) AS varchar) + '-' + CAST(Month(LogTime) AS varchar)

My problem is that the table tblProdhist contains 14 million rows (one year of data) and that aggregation on this table is extremely slow.
[+][-]01/18/07 02:43 PM, ID: 18345680Accepted Solution

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About this solution

Zone: MS SQL Server
Tags: aggregation, month, optimization
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Solution Provided By: angelIII
Participating Experts: 2
Solution Grade: A
 
[+][-]01/18/07 06:17 AM, ID: 18340956Expert Comment

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