How to do multi sort in Elastic Search - php

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

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!

Answer 2

#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);