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Message Posted: Fri, 12 Nov 2004 @ 09:44:54 GMT
| Subj: | | Re: Fieldstatistics vs lastaltertimestamp in TVFields |
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| From: | | Dieter Noeth |
| | Would someone be able to explain to me the difference (or more so FieldStatistics) between the LastAlterTimestamp column verse the
FieldStatistics column in DBC.TVFields? | |
| | I understand that FieldStatistics holds the index and column histograms. Inside the field is the (and I quote from Teradata RDBMS SQL
Reference manual) "Time the statistics were collected." I have written SQL to extract this date but when compared to the LastAlterTimestamp date
there is a big difference. It appears that the LastAlterTimestamp is actually holding the correct date as to when the last time we collected
statistics on a particular column. It also appears that the LastAlterTimestamp date is the same as the date when doing a Statistics command in
Teradata Administrator. So what date is kept with in the FieldStatistics column? | |
Interesting...
I never noticed that before :-(
But it's easy to explain ;-)
LastAlterTimestamp -> Start time of Collect Stats
FieldStatistics -> Time when FieldStats where updated
So, if it's a Collect Stats on a single column, the difference is the time needed to collect those stats...
Dieter
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