On 4/14/08, Chris Tracy <[EMAIL PROTECTED]> wrote:
> > If you need to do this from the shell, I'm not sure there is anything
> > you can do. If you're doing this from the C API just look for timestamps
> > that are >= your target and terminate the query as soon as you find one
> > larger than the target timestamp (e.g. stop calling step() and call
> > reset() on the statement). If the number of datapoints at a given
> > timestamp is known (because it is fixed, or because you stashed that
> > value in another table), you could also use a LIMIT clause. That has
> > the added bonus of doing the right thing (even if it takes longer) if
> > the rows somehow get out-of-order.
>
>
> I'm actually using Perl's DBI interface. Not sure that I can
> easily do the exit when seeing a timestamp one bigger than the one I'm
> after, but it's an intriguing idea I'd not considered before. The LIMIT
> I'd also considered, but since the data is variable, I'd abandoned it.
> Hadn't considered storing the value in another table. But since the whole
> thing was based on an invalid premise (that SQLite was somehow magically
> finding the initial value quickly, ignoring that it just happened to be
> closer to the start of the db) I think I'll take another approach to
> solving the problem.
>
heck, I didn't realize you were using Perl (I thought you were working
in some highly constrained environment with 2 bytes of memory, like
the Mars rover or something).
Just exit the loop.
my $timestamp = 1167615600;
while ($ary_ref = $sth->fetch) {
last if $ary_ref->[0] > $timestamp;
do other stuff...
}
what's the problem? It should be blindingly fast.
> Thanks for the input though,
>
>
> Chris
>
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--
Puneet Kishor http://punkish.eidesis.org/
Nelson Institute for Environmental Studies http://www.nelson.wisc.edu/
Open Source Geospatial Foundation (OSGeo) http://www.osgeo.org/
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