How to use DISCARD in redis

RedisHow-ToBeginner · 3 min read

How to Use DISCARD Command in Redis Transactions

In Redis, DISCARD is used to cancel a transaction started with MULTI and discard all queued commands. It aborts the transaction without executing any commands, returning the connection to normal mode.

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Syntax

The DISCARD command is used after starting a transaction with MULTI. It cancels the transaction and clears all queued commands.

DISCARD: Cancels the current transaction.

redis

MULTI
DISCARD

Output

+OK

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Example

This example shows starting a transaction with MULTI, queuing commands, then cancelling the transaction with DISCARD. No commands are executed.

redis

127.0.0.1:6379> MULTI
OK
127.0.0.1:6379> SET key1 "value1"
QUEUED
127.0.0.1:6379> SET key2 "value2"
QUEUED
127.0.0.1:6379> DISCARD
OK
127.0.0.1:6379> GET key1
(nil)

Output

(nil)

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Common Pitfalls

One common mistake is to forget that DISCARD only works inside a transaction started by MULTI. Using DISCARD without MULTI returns an error. Also, after DISCARD, the transaction is cancelled and queued commands are lost.

Wrong usage example:

redis

127.0.0.1:6379> DISCARD
(error) ERR DISCARD without MULTI

Output

(error) ERR DISCARD without MULTI

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Quick Reference

Command	Description
MULTI	Start a transaction and queue commands
DISCARD	Cancel the transaction and discard queued commands
EXEC	Execute all queued commands in the transaction

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Key Takeaways

Use DISCARD only after MULTI to cancel a Redis transaction.

DISCARD clears all queued commands without executing them.

Using DISCARD outside a transaction causes an error.

After DISCARD, the connection returns to normal command mode.