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Redis bitmaps are an extension of the string data type that lets you treat a string like a bit vector. You can also perform bitwise operations on one or more strings. Some examples of bitmap use cases include:

Efficient set representations for cases where the members of a set correspond to the integers 0-N.
Object permissions, where each bit represents a particular permission, similar to the way that file systems store permissions.

Examples

Suppose you have 1000 sensors deployed in the field, labeled 0-999. You want to quickly determine whether a given sensor has pinged the server within the hour.

You can represent this scenario using a bitmap whose key references the current hour.

Sensor 123 pings the server on January 1, 2024 within the 00:00 hour.
```
> SETBIT pings:2024-01-01-00:00 123 1
(integer) 0
```
Did sensor 123 ping the server on January 1, 2024 within the 00:00 hour?
```
> GETBIT pings:2024-01-01-00:00 123
1
```
What about server 456?
```
> GETBIT pings:2024-01-01-00:00 456
0
```

Basic commands

SETBIT sets a bit at the provided offset to 0 or 1.
GETBIT returns the value of a bit at a given offset.
BITOP lets you perform bitwise operations against one or more strings.

See the complete list of bitmap commands.

Performance

SETBIT and GETBIT are O(1). BITOP is O(n), where n is the length of the longest string in the comparison.

Learn more

Redis Bitmaps Explained teaches you how to use bitmaps for map exploration in an online game.
Redis University's RU101 covers Redis bitmaps in detail.

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