elastic

DSL 语法

Match 查询（全文搜索）：

// 基础 match 查询
req := &SearchRequest{
    Query: map[string]any{
        "match": map[string]any{
            "message": "hello world",
        },
    },
}

// match_phrase（短语匹配，要求词序一致）
req := &SearchRequest{
    Query: map[string]any{
        "match_phrase": map[string]any{
            "message": "hello world",
        },
    },
}

// multi_match（多字段匹配）
req := &SearchRequest{
    Query: map[string]any{
        "multi_match": map[string]any{
            "query": "hello world",
            "fields": []string{"message", "title", "content"},
        },
    },
}

Term 查询（精确匹配）：

// 单个 term 查询
req := &SearchRequest{
    Query: map[string]any{
        "term": map[string]any{
            "status": "active",
        },
    },
}

// terms 查询（多值匹配）
req := &SearchRequest{
    Query: map[string]any{
        "terms": map[string]any{
            "status": []string{"active", "pending"},
        },
    },
}

Range 查询（范围查询）：

req := &SearchRequest{
    Query: map[string]any{
        "range": map[string]any{
            "age": map[string]any{
                "gte": 18,
                "lte": 30,
            },
        },
    },
}

// 日期范围查询
req := &SearchRequest{
    Query: map[string]any{
        "range": map[string]any{
            "created_at": map[string]any{
                "gte": "2024-01-01",
                "lte": "now",
                "format": "yyyy-MM-dd",
            },
        },
    },
}

Bool 查询（组合查询）：

req := &SearchRequest{
    Query: map[string]any{
        "bool": map[string]any{
            // must: AND 关系，必须满足
            "must": []map[string]any{
                {
                    "match": map[string]any{
                        "title": "search keyword",
                    },
                },
                {
                    "term": map[string]any{
                        "status": "active",
                    },
                },
            },
            // should: OR 关系，可以满足
            "should": []map[string]any{
                {
                    "term": map[string]any{
                        "tag": "important",
                    },
                },
            },
            // must_not: NOT 关系，必须不满足
            "must_not": []map[string]any{
                {
                    "term": map[string]any{
                        "status": "deleted",
                    },
                },
            },
            // filter: 过滤，不计算相关性得分
            "filter": []map[string]any{
                {
                    "range": map[string]any{
                        "created_at": map[string]any{
                            "gte": "2024-01-01",
                        },
                    },
                },
            },
        },
    },
}

嵌套查询（Nested Query）：

req := &SearchRequest{
    Query: map[string]any{
        "nested": map[string]any{
            "path": "comments",
            "query": map[string]any{
                "bool": map[string]any{
                    "must": []map[string]any{
                        {
                            "match": map[string]any{
                                "comments.text": "great",
                            },
                        },
                    },
                },
            },
        },
    },
}

聚合查询（Aggregations）：

req := &SearchRequest{
    Size: new(0), // 只要聚合、不要命中时设为 0；不设 Size 就按集群默认返回 10 条
    Query: map[string]any{
        "match_all": map[string]any{},
    },
    Aggs: map[string]any{
        "status_count": map[string]any{
            "terms": map[string]any{
                "field": "status",
            },
        },
        "avg_age": map[string]any{
            "avg": map[string]any{
                "field": "age",
            },
        },
    },
}

排序：

不设 Sort 时按相关度（_score）排序，每条命中带 Score；只有 search_after 必须配 Sort，缺了在发请求前就报错。排序方向只认 asc、desc（大小写都行），字段名不能为空，写错了同样在发请求前报错。

req := &SearchRequest{
    Query: map[string]any{
        "match_all": map[string]any{},
    },
    Sort: []map[string]any{
        {
            "created_at": map[string]any{
                "order": "desc",
            },
        },
        {
            "_score": map[string]any{
                "order": "desc",
            },
        },
    },
}

分页：

req := &SearchRequest{
    Query: map[string]any{
        "match_all": map[string]any{},
    },
    From: 0,       // 起始位置
    Size: new(10), // 每页大小
}

总数：

结果的 Total 要和 TotalRelation 一起读：TotalRelationEq 是准确值；TotalRelationGte 表示集群数到一万就停了，实际至少这么多。要准确总数时在请求里打开 TrackTotalHits：

req := &SearchRequest{
    Query: map[string]any{
        "match_all": map[string]any{},
    },
    TrackTotalHits: true,
}

建议

1. 对于精确匹配使用 term 查询
2. 对于全文搜索使用 match 查询
3. 使用 bool 查询组合多个条件
4. 使用 filter 进行过滤可以提高性能
5. 合理使用分页避免深分页问题

示例

// 复杂查询示例
req := &SearchRequest{
    Query: map[string]any{
        "bool": map[string]any{
            "must": []map[string]any{
                {
                    "match": map[string]any{
                        "title": "search keyword",
                    },
                },
            },
            "filter": []map[string]any{
                {
                    "term": map[string]any{
                        "status": "active",
                    },
                },
                {
                    "range": map[string]any{
                        "created_at": map[string]any{
                            "gte": "2024-01-01",
                            "lte": "now",
                        },
                    },
                },
            },
        },
    },
    Sort: []map[string]any{
        {
            "created_at": map[string]any{
                "order": "desc",
            },
        },
    },
    From: 0,
    Size: new(20),
}