PFMERGE

Syntax text Syntax diagram API methods

PFMERGE destkey [sourcekey [sourcekey ...]]

Client:

pfmerge(
    dest: KeyT,  // The destination key
    *sources: KeyT  // One or more source HyperLogLog keys
) → ResponseT  // OK

PFMERGE(
    destination: RedisArgument,  // The destination key to merge to
    sources: RedisVariadicArgument  // One or more source keys to merge from
) → SimpleStringReply  // OK

pfmerge(
    destkey: byte[],  // The destination key
    sourcekeys: byte[]...  // One or more source keys
) → String  // OK

pfmerge(
    destkey: String,  // The destination key
    sourcekeys: String...  // One or more source keys
) → String  // OK

pfmerge(
    destkey: K,  // The destination key
    sourcekeys: K...  // The source keys
) → String  // OK

pfmerge(
    destkey: K,  // The destination key
    sourcekeys: K...  // The source keys
) → RedisFuture<String>  // OK

pfmerge(
    destkey: K,  // The destination key
    sourcekeys: K...  // The source keys
) → Mono<String>  // OK

PFMerge(
    ctx: context.Context,  // Context for the command
    dest: string,  // The destination key
    keys: ...string  // One or more source keys
) → *StatusCmd  // OK

HyperLogLogMerge(
    destination: RedisKey,  // The key of the merged HyperLogLog
    first: RedisKey,  // First source key
    second: RedisKey,  // Second source key
    flags: CommandFlags  // The flags to use for this operation
) → void

HyperLogLogMerge(
    destination: RedisKey,  // The key of the merged HyperLogLog
    sourceKeys: RedisKey[],  // The keys of the HyperLogLogs to merge
    flags: CommandFlags  // The flags to use for this operation
) → void

HyperLogLogMergeAsync(
    destination: RedisKey,  // The key of the merged HyperLogLog
    first: RedisKey,  // First source key
    second: RedisKey,  // Second source key
    flags: CommandFlags  // The flags to use for this operation
) → Task

HyperLogLogMergeAsync(
    destination: RedisKey,  // The key of the merged HyperLogLog
    sourceKeys: RedisKey[],  // The keys of the HyperLogLogs to merge
    flags: CommandFlags  // The flags to use for this operation
) → Task

pfmerge(
    $destinationKey: string,  // The destination key
    $sourceKeys: array|string  // One or more source keys
) → mixed  // OK

pfmerge(
    dstkey: D,  // The destination key
    srckeys: S  // The source keys
) → ()

pfmerge(
    dstkey: D,  // The destination key
    srckeys: S  // The source keys
) → ()

Available since:: Redis Open Source 2.8.9
Time complexity:: O(N) to merge N HyperLogLogs, but with high constant times.
ACL categories:: @write, @hyperloglog, @slow,
Compatibility:: Redis Software and Redis Cloud compatibility

Note:

This command's behavior varies in clustered Redis environments. See the multi-key operations page for more information.

Merge multiple HyperLogLog values into a unique value that will approximate the cardinality of the union of the observed sets of the source HyperLogLog structures.

The computed merged HyperLogLog is set to the destination variable, which is created if it does not exist (defaulting to an empty HyperLogLog).

If the destination variable exists, it is treated as one of the source sets and its cardinality will be included in the cardinality of the computed HyperLogLog.

Required arguments

destkey

The destination HyperLogLog key in which to store the merged result.

Optional arguments

sourcekey [sourcekey ...]

One or more source HyperLogLog keys to merge into destkey. destkey itself is also included in the merge.

Examples

Redis Software and Redis Cloud compatibility

Redis Software	Redis Cloud	Notes
✅ Standard ✅ Active-Active	✅ Standard ✅ Active-Active

Return information

RESP2 RESP3

Simple string reply: OK.