Redis Sets: SUNIONSTORE

Redis SUNIONSTORE Command

Redis SUNIONSTORE command is used to store, the members of the set resulting from the union of all the given sets in a specific key. Keys that do not exist are considered to be empty sets and overwritten if specified key already exists.

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

• Union Storage: Computes the union of multiple sets and stores the result in a new set.
• Data Aggregation: Aggregates elements from several sets into a single set for easier management and retrieval.
• Intermediate Results: Useful for storing intermediate results of set operations for later use or further processing.
• Efficient Set Operations: Provides a way to perform union operations and store the result efficiently in a single step.

Syntax:

SUNIONSTORE DESTINATION KEY KEY1..KEYN

Available since:

1.0.0.

Return Value:

Integer replies the number of elements in the resulting set.

Return Value Type:

Integer

Example : Redis SUNIONSTORE : Using two sets

mycolor1 = {R G B} 

mycolor2 = {G B Y}

SUNIONSTORE dest_key mycolor1 mycolor2 = {R G B Y}

127.0.0.1:6379> SADD mycolor1 R G B
(integer) 3
127.0.0.1:6379> SADD mycolor2 G B Y
(integer) 3
127.0.0.1:6379> SUNIONSTORE dest_key mycolor1 mycolor2
(integer) 4
127.0.0.1:6379> SMEMBERS dest_key
1) "G"
2) "B"
3) "Y"
4) "R"

Example : Redis SUNIONSTORE : Using three sets

mycolor1 = {R G B} 

mycolor2 = {G B Y}

mycolor3 = {B O P}

SUNIONSTORE dest_key mycolor1 mycolor2 mycolor3 = {R G B Y O P}

If the destination key already exists, the existing contents will be erased, and written this new set.

127.0.0.1:6379> SADD mycolor3 B O P
(integer) 3
127.0.0.1:6379> SUNIONSTORE dest_key mycolor1 mycolor2 mycolor3
(integer) 6
127.0.0.1:6379> SMEMBERS dest_key
1) "Y"
2) "R"
3) "O"
4) "P"
5) "G"
6) "B"

Example : Redis SUNIONSTORE : destination key can be assigned to a source key

mycolor1 = {R G B} 

mycolor2 = {G B Y}

mycolor3 = {B O P}

SUNIONSTORE mycolor1 mycolor1 mycolor2 mycolor3

the existing contents of mycolor1 are cleared, the results are entered in mycolor1.

127.0.0.1:6379> SUNIONSTORE mycolor1 mycolor1 mycolor2 mycolor3
(integer) 6
127.0.0.1:6379> SMEMBERS mycolor1
1) "Y"
2) "R"
3) "O"
4) "P"
5) "G"
6) "B"

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