Concept Flow - SUNION, SINTER, SDIFF set operations
Start with Sets A and B
Perform Set Operation
Return Resulting Set
End
Start with two sets, pick one of the operations (union, intersection, difference), perform it, and get the resulting set.
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SUNION, SINTER, SDIFF set operations in Redis - Step-by-Step Execution
Execution Sample
Redis
SADD setA 1 2 3 SADD setB 2 3 4 SUNION setA setB SINTER setA setB SDIFF setA setB
Add elements to two sets, then perform union, intersection, and difference operations.
Execution Table
| Step | Command | SetA | SetB | Operation | Result |
|---|---|---|---|---|---|
| 1 | SADD setA 1 2 3 | 1,2,3 | - | - | - |
| 2 | SADD setB 2 3 4 | 1,2,3 | 2,3,4 | - | - |
| 3 | SUNION setA setB | 1,2,3 | 2,3,4 | Union | 1,2,3,4 |
| 4 | SINTER setA setB | 1,2,3 | 2,3,4 | Intersection | 2,3 |
| 5 | SDIFF setA setB | 1,2,3 | 2,3,4 | Difference | 1 |
| 6 | SDIFF setB setA | 1,2,3 | 2,3,4 | Difference | 4 |
| 7 | End | 1,2,3 | 2,3,4 | - | - |
💡 All operations performed. Sets remain unchanged by SUNION, SINTER, SDIFF (read-only operations).
Variable Tracker
| Variable | Start | After 1 | After 2 | After 3 | After 4 | After 5 | Final |
|---|---|---|---|---|---|---|---|
| setA | empty | 1,2,3 | 1,2,3 | 1,2,3 | 1,2,3 | 1,2,3 | 1,2,3 |
| setB | empty | empty | 2,3,4 | 2,3,4 | 2,3,4 | 2,3,4 | 2,3,4 |
| Result | none | none | none | 1,2,3,4 | 2,3 | 1 | 1 (last result) |
Key Moments - 3 Insights
Why does SUNION return all unique elements from both sets?
SUNION combines all elements from both sets without duplicates, as shown in step 3 of the execution_table where the result is 1,2,3,4.
Why does SINTER return only elements present in both sets?
SINTER returns the common elements found in both sets, demonstrated in step 4 where the result is 2,3, which appear in both setA and setB.
Why does SDIFF setA setB return elements only in setA?
SDIFF returns elements in the first set that are not in the second. Step 5 shows result 1, which is in setA but not in setB.
Visual Quiz - 3 Questions
Test your understanding
Look at the execution_table at step 4, what is the result of SINTER setA setB?
💡 Hint
Check the 'Result' column at step 4 in the execution_table.
At which step does the SDIFF operation return the element '1'?
💡 Hint
Look at the 'Operation' and 'Result' columns in the execution_table for SDIFF returning '1'.
If we add element '5' to setB before step 3, how would SUNION result change?
💡 Hint
SUNION returns all unique elements from both sets, so adding '5' to setB adds it to the union.
Concept Snapshot
SUNION key1 key2 ... - returns all unique elements from all sets combined SINTER key1 key2 ... - returns elements common to all sets SDIFF key1 key2 ... - returns elements in first set not in others All commands operate on Redis sets and return a set result Sets remain unchanged after these operations
Full Transcript
This visual execution traces Redis set operations SUNION, SINTER, and SDIFF. We start by adding elements to two sets, setA and setB. SUNION combines all unique elements from both sets, shown as 1,2,3,4. SINTER returns only elements present in both sets, which are 2 and 3. SDIFF returns elements in the first set not in the second; for setA minus setB, the result is 1. The sets themselves do not change after these operations. This step-by-step trace helps understand how these set operations work in Redis.