CouchBase 索引嵌套元素

Question

在 CouchBase(4.1.1) 中，以这两个示例为例，N1QL 可以使用整个元素创建索引。

假设我们有这样的文档结构：

{
   "name": "blah",
   "credentials": [
       {
          "level": 5,
          "sector": "XP"
       }
   ],
}

现在假设我们想根据名称和整个凭证元素创建索引 1，这可能吗？

类似于

create index indexName on `bucketName` (name, credentials) USING GSI;

或 index2 基于名称和嵌套字段之一，如级别；这怎么可能呢？像

create index indexName on `bucketName`(name, credential.levels) USING GSI;

当运行说明我的二级索引没有被使用并且 couchbase 默认为这个桶的主索引。

这是我正在使用的select。

select s.name, s.credentials 
from `security` unnest s.credentials
where credentials is not missing and name = 'tom';

这是生成的说明：

{
    "requestID": "f8d46eeb-3898-4ace-a24f-1582e0504eb7",
    "signature": "json",
    "results": [
        {
            "#operator": "Sequence",
            "~children": [
                {
                    "#operator": "PrimaryScan",
                    "index": "#primary",
                    "keyspace": "read",
                    "namespace": "default",
                    "using": "gsi"
                },
                {
                    "#operator": "Parallel",
                    "~child": {
                        "#operator": "Sequence",
                        "~children": [
                            {
                                "#operator": "Fetch",
                                "as": "s",
                                "keyspace": "bucketName",
                                "namespace": "default"
                            },
                            {
                                "#operator": "Unnest",
                                "as": "beacons",
                                "expr": "(`s`.`credentials`)"
                            },
                            {
                                "#operator": "Filter",
                                "condition": "((`s`.`name`) = \"tom\")"
                            },
                            {
                                "#operator": "InitialProject",
                                "result_terms": [
                                    {
                                        "expr": "(`s`.`id`)"
                                    },
                                    {
                                        "expr": "`credentials`"
                                    }
                                ]
                            },
                            {
                                "#operator": "FinalProject"
                            }
                        ]
                    }
                }
            ]
        }
    ],
    "status": "success",
    "metrics": {
        "elapsedTime": "2.82063ms",
        "executionTime": "2.765439ms",
        "resultCount": 1,
        "resultSize": 1917
    }
}

Answer 1

以下查询应使用您的索引。

select s.name, s.credentials 
from `security` s
where s.credentials is not missing and s.name = 'tom';

select s.name, credentials 
from `security` s unnest s.credentials
where s.credentials is not missing and s.name = 'tom';

Answer 2

根据我的发现，如果您尝试创建索引，则必须排除不包含您正在建立索引的字段的文档。因此，对于我上面的示例，一旦我添加： name is not missing 在 where 语句中，我的查询开始使用我的二级索引。

下面来自 Couchbase site 的简介让我得出了这个发现

Attention: MISSING items are not indexed by indexers. To take advantage of covering indexes and for the index to qualify, a query needs to exclude documents where the index key expression evaluates to MISSING.

CouchBase 索引嵌套元素

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