如何在弹性搜索中进行多重排序

Question

I need to divide my search result into two parts. 1 with those goods in which the number> 0 sort them by price and withdraw first. 2 products whose quantity = 0 sort by price and display at the end, after those products that are in stock. The main thing is that in the first group of goods (whose quantity> 0) there were no goods from the second group (whose quantity = 0) What unfortunately happens when I sort by two conditions

Use PHP 7.1 and Elastic Search 6.6.0

Small example, there is a table of goods

id | site_price | count
 1 | 10         |  0
 2 | 5          |  5
 3 | 15         |  2
 4 | 20         | 10
 5 | 15         |  0

I need to sort first by quantity, and then by price (without losing the first sorting). First sort: ('count'=>'desc') . Second sort: ('site_price'=>'asc') . Should get this result:

id | site_price | count
 2 |  5         | 10
 3 | 15         |  5
 4 | 20         |  2
 1 | 10         |  0
 5 | 15         |  0


$this->params['body'] = array(
    'from' => ($filters['page'] - 1) * 15,
    'size' => 15,
    'query' => array(
        'bool' => array(
            'must' => array(
                "query_string" => array(
                    'query' => "*" . $filters['text'] . "*",
                )
            ),
        )
    ),
    'sort' => array(
        array("shops_count" => "desc"),
        array("site_price" => "asc")
    )
);
$result = $this->client->search($this->params);

Answer 1

@Nikolay, thanks for the help. Unfortunately, this did not help. I tried rewrote the query - but the result is the same. Here is an example: removed too much left only search and sorting

enter code here
$this->params['body'] = array(
        'from' => ($filters['page'] - 1) * 15,
        'size' => 15,
        'query' => array(
            'bool' => array(
                'must' => array(
                    "query_string" => array(
                        'query' => "*" . $filters['text'] . "*",
                    )
                ),
            )
        ),
        'sort' => array(
            array("shops_count" => "desc"),
            array("site_price" => "asc")
        )
    );
        $result = $this->client->search($this->params);

Answer 2

It looks like that you want to achieve behavior similar to UNION in SQL, since you first want to split the result set into 2 groups, sort each group and then attach one group after another.

There are a few ways to do it.

1) By doing 2 queries

Like in this answer , it is suggested to do 2 queries:

POST /orders/_search
{
    "query": {
        "range": {
            "count": {
                "gt": 0
            }
        }
    },
    "sort" : [
        {"site_price": "asc"},
    ]
}

POST /orders/_search
{
    "query": {
        "range": {
            "count": {
                "gte": 0,
                "lte": 0
            }
        }
    },
    "sort" : [
        {"site_price": "asc"},
    ]
}

And then joining them on the client side. There is also a way to do it completely on the Elasticsearch side.

2) By using script sorting

We can use script based sorting and sort first on the availability ( count > 0 ), then by price:

POST /orders/_search
{
    "sort" : [
        {
            "_script" : {
                "type" : "number",
                "script" : {
                    "lang": "painless",
                    "source": "if (doc['count'].value > 0) { 1 } else { 0 } "
                },
                "order" : "desc"
            }
        },
        {"site_price": "asc"}
    ]
}

However, scripting always has performance overhead. Solution #1 is more robust, although it performs 2 queries.

Here is another solution that uses single query and does not use expensive scripting.

3) Adding new field - for sorting

If we add a special field, "available" , we will not need to use script sorting.

The documents might look like this:

doc1 = {
    "id": 1,
    "site_price": 10,
    "count": 0,
    "available": 0
}
doc2 = {
    "id": 2,
    "site_price": 5,
    "count": 5,
    "available": 1
}

Then the sorting will look like this:

POST /orders/_search
{
    "sort" : [
        {"available": "desc"},
        {"site_price": "asc"}
    ]
}

This is a common pattern called denormalization which proves useful when tuning for best performance.

Hope that helps!