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redis
Matthew Scragg
Matthew Scragg

Reputation: 4638

Redis Set Default Order

In a Redis Set (not sorted set). I noticed the values are in the order they are added with the newest being first. I didn't find in the docs if the set will always maintain this order. So my question, can I trust they will always be ordered like this?

Upvotes: 8

Views: 2648

Answers (1)

Sripathi Krishnan
Sripathi Krishnan

Reputation: 31538

In general, you cannot trust the order of the elements. If you want it in a particular order, you either use a list or a sortedset.

A Set is built using a HashTable. There are absolutely no guarantees to the order of the element.

However, if you are set only contains integers, and the number of elements is less than the directive set-max-intset-entries (by default 512) - then the set is built on a structure called IntSet, or Integer Set. An Integer Set is a sorted integer array. The iterator for such a set will return elements in ascending order.

So, more specifically, if you can program to an integer set, you can assume the elements will be in sorted order.

Upvotes: 12

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