Sending multiple commands in pipeline in Redis - Step-by-Step Execution

Concept Flow - Sending multiple commands in pipeline

Start Pipeline

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Queue Command 1

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Queue Command 2

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Queue Command N

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Send All Commands Together

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Receive All Responses

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Process Responses

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End Pipeline

Commands are queued first, then sent all at once to Redis, responses come back together, improving speed.

Execution Sample

Redis

MULTI
SET key1 value1
SET key2 value2
EXEC

Queues two SET commands in a transaction and executes them together.

Execution Table

Step	Action	Command Queued	Pipeline State	Response Received
1	Start pipeline	None	Empty queue	None
2	Queue command	SET key1 value1	Queue: [SET key1 value1]	None
3	Queue command	SET key2 value2	Queue: [SET key1 value1, SET key2 value2]	None
4	Send all commands	MULTI, SET key1 value1, SET key2 value2, EXEC	Queue sent	None
5	Receive responses	None	Queue cleared	Responses: [OK, QUEUED, QUEUED, [OK, OK]]
6	Process responses	None	Empty queue	Commands executed successfully
7	End pipeline	None	Empty queue	Pipeline finished

💡 All queued commands sent and responses received, pipeline ends.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 5	Final
pipeline_queue	[]	[SET key1 value1]	[SET key1 value1, SET key2 value2]	Sent to Redis	[]	[]
responses	[]	[]	[]	[]	[OK, QUEUED, QUEUED, [OK, OK]]	[OK, QUEUED, QUEUED, [OK, OK]]

Key Moments - 2 Insights

Why don't we get responses immediately after queuing each command?

Responses come only after sending all commands together (see step 5 in execution_table), because pipeline queues commands first to send them in bulk.

What happens if we forget to send the queued commands?

Commands stay in the queue and no responses come back (see pipeline_queue state at step 4), so the pipeline never completes.

Visual Quiz - 3 Questions

Look at the execution_table at step 3, what is the pipeline state?

A Queue: [SET key1 value1]

B Queue sent

C Queue: [SET key1 value1, SET key2 value2]

D Empty queue

💡 Hint

Check the 'Pipeline State' column at step 3 in execution_table.

At which step do we receive the responses from Redis?

A Step 5

B Step 4

C Step 2

D Step 7

💡 Hint

Look at the 'Response Received' column in execution_table.

If we add another SET command before sending, how does the pipeline queue change at step 3?

A Queue sent

B Queue: [SET key1 value1, SET key2 value2, SET key3 value3]

C Queue: [SET key1 value1]

D Empty queue

💡 Hint

Refer to variable_tracker for pipeline_queue changes after queuing commands.

Concept Snapshot

Sending multiple commands in pipeline:
- Queue commands first without waiting for responses.
- Send all queued commands together to Redis.
- Receive all responses at once.
- Improves performance by reducing network delays.
- Use MULTI/EXEC or pipeline commands for batching.

Full Transcript

In Redis, sending multiple commands in a pipeline means you first queue commands without waiting for each response. Once all commands are queued, you send them together to Redis. Redis processes them and sends back all responses at once. This reduces the time spent waiting for each command individually, making operations faster. The example shows queuing two SET commands inside a MULTI/EXEC transaction. The execution table traces each step: starting the pipeline, queuing commands, sending them, receiving responses, and finishing. Variables like the pipeline queue and responses change state as commands are queued and sent. Key points include understanding that responses come only after sending all commands, and forgetting to send commands leaves the queue uncleared. The visual quiz tests understanding of pipeline state and response timing. The snapshot summarizes the main idea: queue commands, send together, get responses together, for better speed.