zdiff
Xiangrong Fang
http://groups.google.com/group/redis-db/browse_thread/thread/f17f696761088655?fwc=2
will be added in redis 2.2 or not?
Also,
1) why there are no zunion as sunion, but only zunionstore command?
2) is it possible, if for some reason zdiff is not feasible, add a command like
Z2S zset set
to get a set from a zset, and do it fast :D
BR
Shannon
Josiah Carlson
> I wonder if zdiffstore mentioned here:
>
> http://groups.google.com/group/redis-db/browse_thread/thread/f17f696761088655?fwc=2
>
> will be added in redis 2.2 or not?
I've not heard anything, but now is a good time to get the discussion going :)
> Also,
>
> 1) why there are no zunion as sunion, but only zunionstore command?
With a set, there is no real way to pull down partial blocks of data
without a SORT. Zsets allow you to pull individual items, ranges,
etc. Also, because of transactional pipelines with MULTI/EXEC, the
non-store versions are effectively redundant with regards to commands
(a store can be followed by a delete, making it equivalent to the
non-store version).
> 2) is it possible, if for some reason zdiff is not feasible, add a command like
>
> Z2S zset set
>
> to get a set from a zset, and do it fast :D
Zdiff is possible, I imagine it was lost in the shuffle of all of the
other things to do for the 2.0 release that were more important at the
time. It would be interesting to be able to quickly be able to
convert a zset into a set, as the reverse is already possible with
ZUNIONSTORE/ZINTERSTORE.
Regards,
- Josiah
Xiangrong Fang
only accept ZSET as their parameters.
R.
Shannon
2010/10/21 Josiah Carlson <josiah....@gmail.com>:
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>
Josiah Carlson
sets as input, whose values default to 1.0, but which can be scaled
with the WEIGHTS argument.
- Josiah
George Bashi
I'm not sure the patch will be merged - after submitting it, I spoke with Pieter on IRC and he pointed out that it's difficult to find a valid use-case for ZDIFFSTORE - Pieter and I solved my problem much better by rearranging my data structures!
If there is interest in ZDIFFSTORE then I'd be more than happy to rebase my patch on the latest head.
Cheers,
George
Xiangrong Fang
Why there is no use case? For example, what I am trying to do now:
A bbs has posts, which I plan to put in a zset, because they have time
lines. No there is a set (or zset) recording the post id a user has
already read. I would like to use DIFF to extract all new posts for a
user.
In fact if possible I would suggest to allow diff/union/intersect to
accept hybrid data types, e.g. a set diff a zset etc. But then again,
I don't know how redis works, so this may be impossible.
But I do think there are many valid use cases...
Regards,
Shannon
2010/10/21 George Bashi <ja...@georgebashi.com>: