Delete keys

**Time complexity:** O(N) where N is the number of keys that will be removed. When a key to remove holds a value other than a string, the individual complexity for this key is O(M) where M is the number of elements in the list, set, sorted set or hash. Removing a single key that holds a string value is O(1).

Removes the specified keys. A key is ignored if it does not exist.

## Return value

Integer reply: The number of keys that were removed.

## Examples

```javascript
redis> SET key1 "Hello"
"OK"
redis> SET key2 "World"
"OK"
redis> DEL key1 key2 key3
(integer) 2
redis> 
```

Your task for this lab is to delete `name` and `age` keys out of 4 keys present: `name`, `age`, `gender`, `height`

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Course Introduction

What is Redis exactly?

Why choose Redis?

Redis Hello World

Common operations with Redis

Redis key name convention

Expiring keys in Redis

How expiring keys work in Redis

Connecting Redis with Node.js

Introduction to project

Invalidating Cache

Refreshing data in background

Rate limiting by IP Address

Setting TTL on rate limit

Creating Express.js middleware for rate limiting

Redis Ping

Setting values inside redis

INCR DECR

FLUSHALL

Connecting Node with Redis

Building a cached API with Redis

Building a rate limiter with Redis

Atomicity and Single Threaded

Lists

More on lists

Sets

Transactions

Key patterns

Redis Caching Concepts with Node.js

Introduction

API Caching

Rate limiting

More with Redis