Redis 中的正确集合，允许按字段更新和删除

Question

I want to store a collection of weather forecasts as JSON objects in redis:

{
  "city":"London",
  "weather":"SUNNY",
  "lastPrediction": "..",
  "source":"..."
}

Each item has a unique city name and there would be up to tens of thousand weather forecasts.

I want to be able to add those to the collection, find and update a single item by the city and remove it by the city as well.

I wonder which structure should I use - I especially do not know how to update and delete entries by a certain field.

Answer 1

Since each item has an unique "city", hash works fine for your case.

• you may set multiple items with HSET (If your redis version is < 4.0.0 - then please check HMSET )
• you may access to the individual fields with HGET
• update your fields with HSET again, and delete your fields with HDEL
• if you want to get all the fields then you use HGETALL

here is the demo;

127.0.0.1:6379> HSET london weather SUNNY lastPrediction "foo" source "foobar"
(integer) 3
127.0.0.1:6379> HGET london weather
"SUNNY"
127.0.0.1:6379> HGETALL london
1) "weather"
2) "SUNNY"
3) "lastPrediction"
4) "foo"
5) "source"
6) "foobar"
127.0.0.1:6379> HSET london weather CLOUDY
(integer) 0
127.0.0.1:6379> HGET london weather
"CLOUDY"
127.0.0.1:6379> HDEL london source
(integer) 1
127.0.0.1:6379> HGETALL london
1) "weather"
2) "CLOUDY"
3) "lastPrediction"
4) "foo"
127.0.0.1:6379>

Please consider redis keys and fields are case sensitive.