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Archives of the TeradataForum
Message Posted: Fri, 22 Feb 2002 @ 22:52:30 GMT
| Subj: | | Re: BTEQ Question |
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| From: | | Geoffrey Rommel |
| | Just an observation. At one of my customer sites, we discovered that when you qualify a request and then use SAMPLE, you might get a
FTS anyway. In our testing, it would do the FTS when you qualified with a TIMESTAMP column but with other columns it did the quick
SAMPLE.... | |
I don't claim to know much about this point, but my class notes for Physical Database Design (dated 1996) say, rather cryptically,
"Do not include TIME in any index.... Indexes with TIME are used for insert only, because exact time is unknown." I think they assume that
whenever you use a TIME or TIMESTAMP column in your query, you don't really know the exact time down to the microsecond, so they will ignore
that and do a FTS instead.
--wgr
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