On Tue, 2010-04-13 at 00:45 +0200, Philippe wrote:
> > However, you are also saying there is no way to also take
> into account
> > the "timeFrame" supercolumn in the same API call ? IE, it is
> not
> > possible to get back a data structure keyed by
> > 'key,supercolumn,column' hence y,x and timeframe which I can
> then
> > process to my heart's delight ?
>
>
> If you're talking about constructing predicates to slice on
> both time
> *and* X coordinate, then no. You can omit the super column
> name from the
> ColumnParent and return a slice of super columns (by time
> period)
> complete with all contained sub-columns, but you can't have it
> both
> ways, no.
> Eric, I'm trying to get my head around this...
>
>
> If I "omit the super column name" and do the query as you mentionned
> in your previous email, then you are saying it will return all columns
> corresponding to the column range of all super columns corresponding
> to the key range.
> This means it is possible to get a rectangular slice of the grid AND
> to get the "third dimension" which is time in my case, the only catch
> being that I cannot limit the amount of data retrieved in the 3rd
> dimension (timeframe).
>
>
> Is this correct ?
No, what I mean is that you can perform a slice that returns either
sub-columns, or super columns. In the former, the column names you are
slicing on are the sub-columns (X coords), in the latter it is super
columns (time). So:
On X coords, (same as my previous mail).
get_range_slice(
keyspaceName,
ColumnParent(CFname, timeFrame),
SlicePredicate(
slice_range=SliceRange(xstart, xend, false, colCount)
),
ystart,
yend,
rowCount,
consistencyLevel,
)
The "columns" attribute of the KeySlice structs returned will contain
the sub-columns contained in timeFrame that match your predicate.
On time.
get_range_slice(
keyspaceName,
ColumnParent(CFname, null),
SlicePredicate(
slice_range=SliceRange(timeStart, timeEnd, false, colCount)
),
ystart,
yend,
rowCount,
consistencyLevel,
)
The "columns" attribute of the KeySlice structs returned will contain
the super columns that match the predicate. Each of these super columns
will contain *all* of the sub-columns.
--
Eric Evans
[email protected]
