azure-storage-table/src/Table/TableRestProxy.php
public function mergeEntityAsync(
        $table,
        Entity $entity,
        TableServiceOptions $options = null
    ) {
        return $this->putOrMergeEntityAsyncImpl(
            $table,
            $entity,
            Resources::HTTP_MERGE,
            true,
            $options
        );
    }
public function mergeEntityAsync(
        $table,
        Entity $entity,
        TableServiceOptions $options = null
    ) {
        return $this->putOrMergeEntityAsyncImpl(
            $table,
            $entity,
            Resources::HTTP_MERGE,
            true,
            $options
        );
    }
Creates promise to update an existing entity by updating the entity's
properties. This operation does not replace the existing entity, as the
updateEntity operation does.

@param string              $table   The table name.
@param Entity              $entity  The table entity.
@param TableServiceOptions $options The optional parameters.

@return \GuzzleHttp\Promise\PromiseInterface

@see http://msdn.microsoft.com/en-us/library/windowsazure/dd179392.aspx