MongoDB:如何索引未知字段

问题描述

我们正在存储结构未定义的文档.我的意思是，它具有基本结构(id，user和creationTimestamp)，但也有一个Map<String, Object> values字段，我们可以在其中存储任何结构:

We're storing documents with a undefined structure. I mean, it has a basic structure (id, user and creationTimestamp), but is also there a Map<String, Object> values fields, where we are able to store whichever structure:

public class Metadata {
    private String id;
    private String user;
    private Date creationTimestamp;
    private Map<String, Object> values;
}

示例:

> db.metadata.find();
{
    "_id" : "Doc2Ref2Mdt1",
    "user" : "user1",
    "creationTimestamp" : ISODate("2018-09-24T12:20:56.958Z"),
    "values" : {
        "ambit" : "ctti",
        "departament" : "economia"
    }
},
{
    "_id" : "Doc1Ref2Mdt1",
    "user" : "user2",
    "creationTimestamp" : ISODate("2018-09-24T12:20:56.169Z"),
    "values" : {
        "date" : ISODate("2018-09-24T12:20:56.171Z"),
        "number" : 16,
        "address" : {
        "street" : "Av. Diagonal",
        "location" : "barcelona",
        "credentials" : [
        {
            "password" : "pwd",
            "login" : "main"
        },
        {
            "password" : "pwd",
            "login" : "other",
            "creation" : ISODate("2018-09-24T12:20:56.171Z")
        }],
        "contact" : "contact name",
        "tags" : ["tag1", "tag2"}]
    }
}

因此，您可以看到values可以存储任何结构.

So, you can see values can store any structure.

我需要知道mongodb是否能够自动为所有索引.

I need to know if mongodb is able to automatically index all of them.

我的意思是，当将一个新字段添加"到values中时，例如，values.newfield它会自动被索引.

I mean, when a new field is "added" into values, for example, values.newfield it is indexed automatically.

有什么想法吗?

推荐答案

以您想要的方式无法实现.

Not possible in the way you want it.

您可以在所有字段上尝试文本索引，然后是实际查询.单独的文本搜索可能会导致假阳性匹配，但与常规查询聚合在一起会减少要扫描的数据集，并且在大多数情况下会加快扫描速度.

You can try text index on all fields followed by the actual query. The text search alone may result with false-positive matches, but aggregated with the normal query it will reduce the dataset to scan and in most cases will speed it up.

要牢记一些限制:

• 仅字符串字段将被索引，例如.find({ $text: { $search: "2018-09-24" } })将不会返回任何内容. .find({ $text: { $search: "16" } })
都不会
• 仅全字查询，即无正则表达式.您将需要使用language: "none"保留停用词，并且不要使用词干.像.find({ $text: { $search: "barcel" } })这样的查询将找不到第二个文档.

• only string fields will be indexed, e.g. .find({ $text: { $search: "2018-09-24" } }) won't return anything. Neither will .find({ $text: { $search: "16" } })
• only full words queries, i.e. no regexps. You will need to use language: "none" to keep stopwords and don't use steming. Queries like .find({ $text: { $search: "barcel" } }) won't find the second document.

如果您控制所有写入操作，则可以通过将values映射序列化为写入时的字符串字段来解决第一个限制.然后，您将仅需要在此字段上创建文本索引.

The first limitation can be worked around by serialisation of values map to a string field on write, if you control all writes. Then you will need to create a text index on this field only.

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