Redis Transactions: WATCH key [key ...]

Redis WATCH Command

Redis WATCH command is used to mark the given keys to be watched for conditional execution of a transaction.

Here are some common uses and scenarios for the "WATCH" command:

• Conditional Execution: Monitors one or more keys for changes, allowing the transaction to proceed only if these keys remain unchanged.
• Optimistic Locking: Implements optimistic locking by tracking key modifications to ensure transaction integrity before committing.
• Prevent Data Conflicts: Helps prevent conflicts and ensures that transactions are applied only if no other client has modified the watched keys.
• Transaction Validation: Provides a mechanism to validate that watched keys have not been altered since the transaction began, enabling safe execution of transactional commands.

Syntax:

WATCH key [key ...] 

Available since

2.2.0.

Return Value

Simple string reply: always OK.

Return Value Type

String

Example:

127.0.0.1:6379> WATCH zset
OK
127.0.0.1:6379> MULTI
OK
127.0.0.1:6379> ZREM zset element
QUEUED
127.0.0.1:6379> EXEC
1) (integer) 0

Previous: UNWATCH
Next: Redis Scripting EVAL