Bitmap

Bitmap Commands

Bitmaps are not a separate data type but a set of bit-oriented operations on string values. They allow setting, getting, and counting individual bits, enabling space-efficient storage of boolean flags.

SETBIT

Synopsis: SETBIT key offset value

Set or clear the bit at the given offset in the string value stored at key. The offset is zero-based. Returns the original bit value at that offset.

> SETBIT mybitmap 7 1
(integer) 0
> SETBIT mybitmap 7 0
(integer) 1

GETBIT

Synopsis: GETBIT key offset

Return the bit value at the given offset. Returns 0 if the key does not exist or the offset is beyond the string length.

> SETBIT mybitmap 7 1
(integer) 0
> GETBIT mybitmap 7
(integer) 1
> GETBIT mybitmap 100
(integer) 0

BITCOUNT

Synopsis: BITCOUNT key [start end [BYTE | BIT]]

Count the number of set bits (1s) in a string. Without range arguments, counts all bits. With start/end, counts bits in the specified range.

• BYTE (default) — Interpret start/end as byte offsets.
• BIT — Interpret start/end as bit offsets (Redis 7.0+).

> SET mykey "foobar"
OK
> BITCOUNT mykey
(integer) 26
> BITCOUNT mykey 0 0
(integer) 4
> BITCOUNT mykey 0 0 BIT
(integer) 0

BITOP

Synopsis: BITOP AND | OR | XOR | NOT destkey key [key ...]

Perform a bitwise operation between strings and store the result in destkey. NOT takes exactly one source key. Returns the size of the resulting string in bytes.

> SET key1 "abc"
OK
> SET key2 "abd"
OK
> BITOP AND result key1 key2
(integer) 3
> BITOP NOT inverted key1
(integer) 3

BITPOS

Synopsis: BITPOS key bit [start [end [BYTE | BIT]]]

Find the position of the first bit set to 0 or 1 in a string. Returns -1 if the bit is not found within the range.

> SET mykey "\xff\xf0\x00"
OK
> BITPOS mykey 0
(integer) 12
> BITPOS mykey 1
(integer) 0
> BITPOS mykey 1 2
(integer) -1

BITFIELD

Synopsis: BITFIELD key [GET encoding offset | SET encoding offset value | INCRBY encoding offset increment | OVERFLOW WRAP | SAT | FAIL] ...

Perform arbitrary bitfield integer operations on strings. Supports multiple sub-commands in a single call.

• Encodings: i<bits> for signed, u<bits> for unsigned (e.g., u8, i16).
• OVERFLOW: Controls overflow behavior for SET and INCRBY.

> BITFIELD mykey SET u8 0 200
1) (integer) 0
> BITFIELD mykey GET u8 0
1) (integer) 200
> BITFIELD mykey INCRBY u8 0 100 OVERFLOW SAT
1) (integer) 255

BITFIELD_RO

Synopsis: BITFIELD_RO key [GET encoding offset ...]

A read-only variant of BITFIELD that only supports GET sub-commands. Safe to use on replicas.

> BITFIELD mykey SET u8 0 42
1) (integer) 0
> BITFIELD_RO mykey GET u8 0
1) (integer) 42