PHP操作Elasticsearch时排除Hierarchy字段参与搜索的方法

我的Elasticsearch索引数据结构如下：

"id": "162d2df9-16e0-4171-bc54-52f2b3a4a23c",
"uri": "https://local.test.com/abc",
"title": "Geography",
"dateTime": "2022-06-15T09:32:37+00:00",
"type": "Default",
"hcs": "Primary",
"lE": "1",
"otherData": {
        "id": "57907298-3945-4654-a75a-7278bcb14399",
        "uri": "https://local.test.com/gcsp",
        "title": "GCSP"
    },
"moreData": {
    "id": "48e939c5-c4f3-4cf2-ae2d-8d964682361d",
    "uri": "https://local.test.com/xyz",
    "title": "Default"
},
"Hierarchy": {
    "data": {
        "id": "57907298-3945-4654-a75a-7278bcb14399",
        "title": "GCSP"
    },
    "parent": [
        {
            "id": "162d2df9-16e0-4171-bc54-52f2b3a4a23c",
            "title_fs": "Maths",
            "hcs_p": "Primary",
            "parent": [
                {
                    "id": "ddff7857-f8be-45a1-b41d-aef2207ff66b",
                    "title_fs": "Civics",
                    "hcs_p": "Primary",
                    "parent": [
                        {
                            "id": "24d126e2-464b-499b-b2c0-adcd7a7b7728",
                            "title_fs": "History",
                            "hcs_p": "Primary",
                            "parent": [
                                {
                                    "id": "23a094da-33b8-4960-8daa-8291e6634305",
                                    "title_fs": "Science",
                                    "hcs_p": "Primary",
                                    "parent": [
                                        {
                                            "id": "32de28ab-5bd5-4cd6-9dc9-f9766fcdfab3",
                                            "title_fs": "Subjects",
                                            "hcs_p": "Primary",
                                            "parent": []
                                        }
                                    ]
                                }
                            ]
                        }
                    ]
                }
            ]
        }
    ]
}

我需要在搜索、结果返回环节排除Hierarchy字段的内容，之前尝试的写法没有生效：

['bool']['must'][] = [
    "multi_match" => [
        "operator" => "and",
        "query" => $searchTerm,
        "fields" => ["*", "Hierarchy"]
    ]
];

你之前的写法不生效核心原因有两个：

• fields配置里的*本身就会匹配所有可搜索字段，追加Hierarchy只是重复指定该字段参与匹配，完全没有实现排除逻辑
• Elasticsearch字段通配符规则中，排除指定字段需要在字段名前加-前缀，对于嵌套对象字段，还要同步排除其下所有子字段，否则深层嵌套的子字段依然会参与匹配

1. 搜索匹配阶段排除Hierarchy字段 #

修改multi_match的fields配置，匹配全量字段后显式排除Hierarchy及其所有子字段：

['bool']['must'][] = [
    "multi_match" => [
        "operator" => "and",
        "query" => $searchTerm,
        "fields" => ["*", "-Hierarchy", "-Hierarchy.*"]
    ]
];

注意：如果使用7.x以下版本的Elasticsearch，需要确认indices.query.bool.max_clause_count参数配置足够，避免字段过多触发查询子句数量限制。

2. 结果返回阶段排除Hierarchy字段 #

如果不需要返回结果中包含Hierarchy的内容，在查询最外层加_source过滤规则即可：

[
    "_source" => [
        "excludes" => ["Hierarchy", "Hierarchy.*"]
    ],
    "query" => [
        // 此处放上述bool查询逻辑
    ]
]

永久优化方案 #

如果业务场景永久不需要用Hierarchy字段做检索，最高效的方案是创建索引映射时，给Hierarchy字段设置"index": false，这样该字段不会生成倒排索引，从根源上不参与搜索匹配，还能节省索引存储开销，需要返回字段内容时依然可以从_source中获取。

内容的提问来源于stack exchange，提问作者Bhumi Shah