redis - REDIS：随机访问列表

Question

在 Redis 中保留大型列表（例如 10K 个项目）的最佳方法是什么，我还想通过键有效地检索项目。

似乎 Redis 没有与 Java 的 OrderedHashMap 等效的数据结构，它完成了这一点，所以可能有必要维护一个集合和一个列表并确保它们保持同步。

Answer 1

Use a sorted set;

Add some bookmarks; use current time for score to sort chronologically:

> zadd bookmarks 123 "bk1"
> zadd bookmarks 456 "bk2"
> zadd bookmarks 789 "bk3"
> zadd bookmarks 999 "bk4"

To get a bookmark, you need the index first:

> zrank bookmarks "bk3"
> "3"

...then pull the bookmark by index:

> zrevrange bookmarks 3 3
> "bk3"

If you don't want to use timestamps, you can sort bookmarks lexicographically using "1" for score:

> zadd bookmarks 1 "link_xyz"
> zadd bookmarks 1 "link_abc"
> zadd bookmarks 1 "link_foo"

> zrange bookmarks 0 -1

1) "link_abc"
2) "link_foo"
3) "link_xyz"

The index lookup is O(log(n)), add to that O(log(n)+1) to pull a single member by index; better than O(n) for lists.

Also, if you add the same bookmark twice, redis automatically replaces the previous member, so you avoid duplicates.

Hope it helps,