Search: Add filter_ep_enable_do_weighting to reduce ES payload if weighting is not used

[rebeccahum]

Description

A default ES search request appears to be under the assumption that weighting is always being used: https://github.com/Automattic/ElasticPress/blob/2302acc659745e767ea0908eeb44a81f9dab755d/includes/classes/Feature/Search/Weighting.php#L644-L647

However, if weighting is not being used, we can reduce the payload by not recursively creating subqueries and thus, decrease the total ES query time. More information on the query at hand described in 10up/ElasticPress#2512.

This PR adds the filter filter_ep_enable_do_weighting, which checks to see if a weighting configuration has been saved or if any of the below filters are hooked onto outside of ElasticPress:

• ep_weighting_configuration_for_search
• ep_query_weighting_fields
• ep_weighting_configuration
• ep_weighting_fields_for_post_type

Changelog Description

Plugin Updated: Enterprise Search

Search: Add filter_ep_enable_do_weighting to reduce ES payload if weighting is not used

Checklist

Please make sure the items below have been covered before requesting a review:

• This change works and has been tested locally (or has an appropriate fallback).
• This change works and has been tested on a Go sandbox.
• This change has relevant unit tests (if applicable).
• This change has relevant documentation additions / updates (if applicable).
• I've created a changelog description that aligns with the provided examples.

Steps to Test

1. Spin-up a new site and do a front-end search ?s=hello and see the below ES query being executed:

{
  "from": 0,
  "size": 10,
  "sort": [
    {
      "_score": {
        "order": "desc"
      }
    }
  ],
  "query": {
    "function_score": {
      "query": {
        "bool": {
          "should": [
            {
              "bool": {
                "must": [
                  {
                    "bool": {
                      "should": [
                        {
                          "multi_match": {
                            "query": "hello",
                            "type": "phrase",
                            "fields": [
                              "post_title^1",
                              "post_excerpt^1",
                              "post_content^1",
                              "post_author.display_name^1",
                              "terms.post_tag.name^1",
                              "terms.category.name^1",
                              "terms.ep_custom_result.name^9999"
                            ],
                            "boost": 3
                          }
                        },
                        {
                          "multi_match": {
                            "query": "hello",
                            "fields": [
                              "post_title^1",
                              "post_excerpt^1",
                              "post_content^1",
                              "post_author.display_name^1",
                              "terms.post_tag.name^1",
                              "terms.category.name^1",
                              "terms.ep_custom_result.name^9999"
                            ],
                            "type": "phrase",
                            "slop": 5
                          }
                        }
                      ]
                    }
                  }
                ],
                "filter": [
                  {
                    "match": {
                      "post_type.raw": "post"
                    }
                  }
                ]
              }
            },
            {
              "bool": {
                "must": [
                  {
                    "bool": {
                      "should": [
                        {
                          "multi_match": {
                            "query": "hello",
                            "type": "phrase",
                            "fields": [
                              "post_title^1",
                              "post_excerpt^1",
                              "post_content^1",
                              "post_author.display_name^1",
                              "terms.ep_custom_result.name^9999"
                            ],
                            "boost": 3
                          }
                        },
                        {
                          "multi_match": {
                            "query": "hello",
                            "fields": [
                              "post_title^1",
                              "post_excerpt^1",
                              "post_content^1",
                              "post_author.display_name^1",
                              "terms.ep_custom_result.name^9999"
                            ],
                            "type": "phrase",
                            "slop": 5
                          }
                        }
                      ]
                    }
                  }
                ],
                "filter": [
                  {
                    "match": {
                      "post_type.raw": "page"
                    }
                  }
                ]
              }
            }
          ]
        }
      },
      "functions": [
        {
          "gauss": {
            "post_date_gmt": {
              "scale": "360d",
              "decay": 0.9,
              "offset": "0d"
            }
          }
        },
        {
          "weight": 0.001
        }
      ],
      "score_mode": "multiply",
      "boost_mode": "multiply"
    }
  },
  "post_filter": {
    "bool": {
      "must": [
        {
          "terms": {
            "post_type.raw": [
              "post",
              "page"
            ]
          }
        },
        {
          "terms": {
            "post_status": [
              "publish"
            ]
          }
        }
      ]
    }
  },
  "track_total_hits": true,
  "timeout": "2s"
}

2. Apply PR
3. Do step 1 and see reduced payload:

{
  "from": 0,
  "size": 10,
  "sort": [
    {
      "_score": {
        "order": "desc"
      }
    }
  ],
  "query": {
    "function_score": {
      "query": {
        "bool": {
          "should": [
            {
              "multi_match": {
                "query": "hello",
                "type": "phrase",
                "fields": [
                  "post_title",
                  "post_excerpt",
                  "post_content"
                ],
                "boost": 3
              }
            },
            {
              "multi_match": {
                "query": "hello",
                "fields": [
                  "post_title",
                  "post_excerpt",
                  "post_content"
                ],
                "type": "phrase",
                "slop": 5
              }
            }
          ]
        }
      },
      "functions": [
        {
          "gauss": {
            "post_date_gmt": {
              "scale": "360d",
              "decay": 0.9,
              "offset": "0d"
            }
          }
        },
        {
          "weight": 0.001
        }
      ],
      "score_mode": "multiply",
      "boost_mode": "multiply"
    }
  },
  "post_filter": {
    "bool": {
      "must": [
        {
          "terms": {
            "post_type.raw": [
              "post",
              "page"
            ]
          }
        },
        {
          "terms": {
            "post_status": [
              "publish"
            ]
          }
        }
      ]
    }
  },
  "track_total_hits": true,
  "timeout": "2s"
}

4. Add filter:

add_filter(
	'ep_weighting_configuration_for_search',
	function( $weight_config ) {
		return $weight_config;
	}
);

5. Repeat step 1 and expect to see the original results

[codecov]

Codecov Report

Merging #3340 (f4cc0a7) into develop (0bba658) will increase coverage by 0.12%.
The diff coverage is 94.11%.

❗ Current head f4cc0a7 differs from pull request most recent head 51b34f4. Consider uploading reports for the commit 51b34f4 to get more accurate results

@@              Coverage Diff              @@
##             develop    #3340      +/-   ##
=============================================
+ Coverage      33.00%   33.12%   +0.12%     
- Complexity      3457     3467      +10     
=============================================
  Files            213      213              
  Lines          13603    13620      +17     
=============================================
+ Hits            4489     4511      +22     
+ Misses          9114     9109       -5     

Impacted Files	Coverage Δ
search/includes/classes/class-search.php	84.56% <94.11%> (-0.05%)	⬇️
search/includes/classes/class-queue.php	88.83% <0.00%> (+1.98%)	⬆️

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0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

No Coverage information
0.0% Duplication