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I am new to redis and just start to learn it today. The official website does a good job about what the data types are and how to set them. That part is not hard to understand. But the problem is without queries, data becomes meaningless. I really failed to find any good documentation on how to do queries/searches in the official site.

When googling, I found this question Redis strings vs Redis hashes to represent JSON and people are all ignoring queries. I just don't get it at all. Many people suggest to store JSON as a string value to the key. This looks very crazy to me. How can they query JSON keys later? For example, for a user object to store in either key-value data type or hashes, how to query users whose age is greater than 30? That should be a very basic and simplest query for a database.

Thank you very much for your help. I am very confused.

EDITED:

After long time googling, I figured out a basic concept: redis can only query keys, and value are not searchable. Thus to search values, I have to create keys which contain the value. This answers my second question.

But the first and my primary question is where to find query tutorial in redis official site. Since redis is very different from sql db, the question might be changed to where to find data modeling and query tutorial in redis official site. It seems to do queries, I have to create some kind of special keys first. That makes query tutorial become modeling tutorial in the end.

Btw, for those who are new to redis and confused like me, you can read this article Storing and Querying Objects. Even if it has a little bug in it, it clarifies many thing about how to use redis for query. These kind of information really should go into redis official doc.

sgon00
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I really failed to find any good documentation on how to do queries/searches in the official site.

Check the command manual for how to query different data structures.

How can they query JSON keys later

JSON is NOT a built-in data structure for Redis. If you want to query JSON data you need to build the index with Redis' built-in data structures by yourself, or you might want to try RedisJSON, which is a Redis module for processing JSON data.

for_stack
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  • Thanks for the reply. But the link you provided is just a list of commands, but I am looking for a query tutorial or a query documentation page. Sorry that I am really lost. – sgon00 Feb 24 '19 at 15:55
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    I think [this](https://redis.io/topics/data-types-intro) is a good tutorial for writing and querying built-in data structures. – for_stack Feb 24 '19 at 16:25
  • Sorry that I don't think so. It even doesn't mention a basic concept, the value is not searchable in redis and only keys are searchable. I found this by googling. Redis has very bad documentation/tutorial on queries. – sgon00 Feb 25 '19 at 03:05