Can anyone speak factually about internal cache in Unidata? In short...
I often look at performance and attempt to improve things by changing queries,
using indicies, rewriting source and so on. In doing so I perform timing and
consistently note that the second time a query is performed, it executes
considerably faster than the first.
As an example, here's the first execution of a series of queries:
SELECT H08.CR.DIV.DATA WITH XCDD.HAMP.CMTE.MEMBER="0202736" time=18ms
SELECT H08.CR.DIV.DATA WITH XCDD.DIV EQ "D2" time=988ms
SELECT H08.CR.DIV.DATA WITH XCDD.REV EQ "P" time=5ms
And then immediately peforming these again:
SELECT H08.CR.DIV.DATA WITH XCDD.HAMP.CMTE.MEMBER="0202736" time=18ms
SELECT H08.CR.DIV.DATA WITH XCDD.DIV EQ "D2" time=9ms
SELECT H08.CR.DIV.DATA WITH XCDD.REV EQ "P" time=5ms
To be clear - the difference between 988ms and 9ms is not a typo, it's real.
Likewise this is not the result of server load. I can consistently reproduce
the above scenario with different queries at different times of the day (and
wee hours of the morning with few users).
I'm not complaining - it's a perfectly good feature - it's just hard to get
accurate timings on things so I often perform queries numerous times and dump
the first few executions. Of course, this isn't reality as many queries only
get executed once in a blue moon...
--
Jeff Butera, Ph.D.
Administrative Systems
Hampshire College
[EMAIL PROTECTED]
413-559-5556
"But Mom - Daddy knows everything."
Catherine Butera
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