Menu
Is there a way to compute the difference between two sorted sets (zset) or do I have to use simple sets for this?
Problem:
I want to retrieve every entry in F, in order, that's not in K.
Is this possible using Redis alone or do I have to do the computation on the application? If yes, what is the best way?
EDIT: SDIFF does not suit this purpose as it doesn't allow sorted sets.
463
The difference (subtraction) is defined as follows. The set A−B consists of elements that are in A but not in B. For example if A={1,2,3} and B={3,5}, then A−B={1,2}. In Figure 1.8, A−B is shown by the shaded area using a Venn diagram.
Sorted set is essentially a unique collection of ordered Redis Strings that have a numeric score associated with them. Ordering is based on scores and the string lexicographical order (more on this later). The strings must be unique while the scores might be repeated.
Make a copy of F as a simple set. Let's call it G. Now perform the SDIFF.
Or...
Make a copy of F as a sorted set. Let's call it G. Iterate through K and remove each element from G.
SDIFF really should work on sorted sets, regular sets, or combinations. But, at this time, it does not.
Also, if F is very large, you may see some performance hits when you make a copy of it. In this case, create a set G in your Redis DB that it updated when K is updated. That is, F and G are initially equal. As you add elements to K, remove the element from G.
196
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
