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MSET

Sets the values of multiple keys in one atomic operation.

Syntax​

MSET key value [key value ...]

Parameters​

  • key: The name of each key to set.
  • value: The value to set for each specified key.

Details​

  • Available since: 1.0.1
  • Time complexity: O(N) where N is the number of keys to set.
  • ACL categories: @write, @string, @fast

The MSET command sets the values of one or more keys in a single atomic operation. If a key already exists, its value is overwritten. MSET is faster than performing multiple SET operations separately because it ensures atomicity, meaning that either all the keys are set or none are.

Examples​

Basic Usage​

To set the values for multiple keys:

MSET key1 "value1" key2 "value2" key3 "value3"

This operation will set:

  • key1 to "value1"
  • key2 to "value2"
  • key3 to "value3"

Overwriting Existing Values​

If the keys already exist:

SET key1 "oldvalue1"
SET key2 "oldvalue2"

MSET key1 "newvalue1" key2 "newvalue2"

After this operation, key1 and key2 will be updated to "newvalue1" and "newvalue2" respectively.

Setting a Mix of New and Existing Keys​

If some keys exist and others do not:

SET key1 "value1"

MSET key1 "newvalue1" key2 "value2"

This will set key1 to "newvalue1" and create key2 with the value "value2".

Edge Cases​

  • If an odd number of arguments is provided (e.g., missing a value for a key), the command will return an error.
  • If any key holds a value that is not a string, an error is returned.
  • MSET does not return any data; it only performs the operation.

RESP2/RESP3 Reply​

  • Simple string reply: OK if the operation was successful.