RENAME and RENAMENX in Redis - Step-by-Step Execution

Concept Flow - RENAME and RENAMENX

Start

↓

Check if source key exists

Yes↓

For RENAME:

↓

Rename key, overwrite if target exists

↓

Return OK

↓

End

↓

For RENAMENX:

↓

Check if target key exists

No↓

Rename key

↓

Return 1

↓

End

↓

If target exists in RENAMENX

↓

Do not rename

↓

Return 0

↓

End

The flow checks if the source key exists, then for RENAME it renames and overwrites target if exists, while RENAMENX renames only if target does not exist.

Execution Sample

Redis

SET key1 "Hello"
SET key2 "World"
RENAME key1 key2
RENAMENX key2 key3

This sequence sets two keys, renames key1 to key2 (overwriting key2), then tries to rename key2 to key3 only if key3 does not exist.

Execution Table

Step	Command	Source Key Exists?	Target Key Exists?	Action	Result	State Change
1	SET key1 "Hello"	N/A	N/A	Set key1	OK	key1 = "Hello"
2	SET key2 "World"	N/A	N/A	Set key2	OK	key2 = "World"
3	RENAME key1 key2	Yes	Yes	Rename key1 to key2, overwrite key2	OK	key2 = "Hello", key1 deleted
4	RENAMENX key2 key3	Yes	No	Rename key2 to key3	1	key3 = "Hello", key2 deleted

💡 Commands complete; RENAMENX skips rename if target exists, RENAME always renames and overwrites.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4
key1	null	"Hello"	"Hello"	deleted	deleted
key2	null	null	"World"	"Hello"	deleted
key3	null	null	null	null	"Hello"

Key Moments - 2 Insights

Why does RENAME overwrite the target key but RENAMENX does not?

RENAME always renames the source key to the target key, deleting the target if it exists (see step 3 in execution_table). RENAMENX only renames if the target key does not exist, otherwise it does nothing and returns 0 (see step 4).

What happens to the source key after a successful rename?

After renaming, the source key is deleted and no longer exists in the database (see variable_tracker after step 3 and 4).

Visual Quiz - 3 Questions

Look at the execution_table at step 3. What is the value of key2 after RENAME key1 key2?

A "World"

B "Hello"

C null

D "key1"

💡 Hint

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

At which step does the source key get deleted?

A After step 3

B After step 1

C After step 2

D After step 4

💡 Hint

Look at variable_tracker for key1 after step 3.

If key3 already existed before step 4, what would RENAMENX return?

A 1

B OK

C 0

D Error

💡 Hint

Refer to the concept_flow and execution_table logic for RENAMENX behavior.

Concept Snapshot

RENAME sourceKey targetKey
- Renames sourceKey to targetKey
- Overwrites targetKey if exists
- Returns OK

RENAMENX sourceKey targetKey
- Renames only if targetKey does NOT exist
- Returns 1 if renamed, 0 if not
- Source key deleted after rename

Full Transcript

This visual execution trace shows how Redis commands RENAME and RENAMENX work. First, keys are set with values. RENAME renames a source key to a target key, overwriting the target if it exists, and deletes the source key. RENAMENX renames only if the target key does not exist, otherwise it does nothing. The variable tracker shows key values after each step. Key moments clarify why RENAME overwrites but RENAMENX does not, and what happens to the source key after renaming. The quiz tests understanding of key states and command results.