.NET ElasticSearch NEST - 用于部分匹配的多个字段的 NGram 分析器

Question

我正在尝试使用 ElasticSearch 在使用 NGram 的多个字段上进行部分匹配，但在构建索引后我匹配 0 个结果。这对我来说不是很自然，而且我什至无法让 NGram 为一个领域工作。这对我来说是一个充满激情的项目，我真的希望新的搜索能够用于部分单词匹配。我尝试使用模糊性，但它开始将错误匹配得分过高。

索引创建：

var nGramFilters = new List<string> { "lowercase", "asciifolding", "nGram_filter" };

Client.Indices.Create(CurrentIndexName, c => c
    .Settings(st => st
            .Analysis(an => an // https://stackoverflow.com/questions/38065966/token-chars-mapping-to-ngram-filter-elasticsearch-nest
                .Analyzers(anz => anz
                    .Custom("ngram_analyzer", cc => cc
                        .Tokenizer("ngram_tokenizer")
                            .Filters(nGramFilters))
                        )
                        .Tokenizers(tz => tz
                                .NGram("ngram_tokenizer", td => td
                                    .MinGram(2)
                                        .MaxGram(20)
                                        .TokenChars(
                                            TokenChar.Letter,
                                            TokenChar.Digit,
                                            TokenChar.Punctuation,
                                            TokenChar.Symbol
                                        )
                                    )
                                )
                            )
                        )
                        .Map<Package>(map => map
                            .AutoMap()
                            .Properties(p => p
                            .Text(t => t
                                .Name(n => n.Title)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                            .Text(t => t
                                .Name(n => n.Summary)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                            .Text(t => t
                                .Name(n => n.PestControlledBy)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                            .Text(t => t
                                .Name(n => n.PesticideControlsThesePests)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                            .Text(t => t
                                .Name(n => n.PesticideInstructions)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                            .Text(t => t
                                .Name(n => n.PesticideActiveIngredients)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                            .Text(t => t
                                .Name(n => n.PesticidesContainingThisActiveIngredient)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                            .Text(t => t
                                .Name(n => n.PesticideSafeOn)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                            .Text(t => t
                                .Name(n => n.PesticideNotSafeOn)
                                .Fields(f => f
                                    .Keyword(k => k
                                        .Name("keyword")
                                            .IgnoreAbove(256)
                                    )
                                    .Text(tt => tt
                                        .Name("ngram")
                                        .Analyzer("ngram_analyzer")
                                    )
                                )
                            )
                        )
                    )
                );

查询：

var result = _client.Search<Package>(s => s
.From((form.Page - 1) * form.PageSize)
.Size(form.PageSize)
.Query(query => query
    .MultiMatch(m => m
        .Fields(f => f
            .Field(p => p.Title.Suffix("ngram"), 1.5)
            .Field(p => p.Summary.Suffix("ngram"), 1.1)
            .Field(p => p.PestControlledBy.Suffix("ngram"), 1.0)
            .Field(p => p.PesticideControlsThesePests.Suffix("ngram"), 1.0)
            .Field(p => p.PesticideInstructions.Suffix("ngram"), 1.0)
            .Field(p => p.PesticideActiveIngredients.Suffix("ngram"), 1.0)
            .Field(p => p.PesticidesContainingThisActiveIngredient.Suffix("ngram"), 1.0)
            .Field(p => p.PesticideSafeOn.Suffix("ngram"), 1.0)
            .Field(p => p.PesticideNotSafeOn.Suffix("ngram"), 1.0)
        )
        .Operator(Operator.Or) // https://stackoverflow.com/questions/46139028/elasticsearch-how-to-do-a-partial-match-from-your-query
        .Query(form.Query)
    )
)
.Highlight(h => h
    .PreTags("<strong>")
    .PostTags("</strong>")
    .Encoder(HighlighterEncoder.Html) //https://github.com/elastic/elasticsearch-net/issues/3091
    .Fields(fs => fs
        .Field(f => f.Summary.Suffix("ngram")),
        fs => fs
        .Field(p => p.PestControlledBy.Suffix("ngram")),
        fs => fs
        .Field(p => p.PesticideControlsThesePests.Suffix("ngram")),
        fs => fs
        .Field(p => p.PesticideInstructions.Suffix("ngram")),
        fs => fs
        .Field(p => p.PesticideActiveIngredients.Suffix("ngram")),
        fs => fs
        .Field(p => p.PesticidesContainingThisActiveIngredient.Suffix("ngram")),
        fs => fs
        .Field(p => p.PesticideSafeOn.Suffix("ngram")),
        fs => fs
        .Field(p => p.PesticideNotSafeOn.Suffix("ngram"))
        .NumberOfFragments(10)
        .FragmentSize(250)
        )
    )
);

我在正确的球场上吗？我尝试使用默认分析器，但我不匹配“猫蒲公英”和“猫耳蒲公英”之类的东西。使用默认分析器......整个单词必须匹配，但我希望部分匹配能够获得“花瓣”和“花瓣”之类的东西。朝着正确方向迈出的任何一步都值得赞赏。我对 ElasticSearch 和 NEST 完全陌生，现在只使用了一周左右。

Answer 1

client.Indices.Create调用无效，原因有二：

1. MinGram 和 MaxGram 之间的差值不能大于 1，因此会出现此错误

Elasticsearch.Net.ElasticsearchClientException: Request failed to execute. Call: Status code 400 from: PUT /my_index1?pretty=true&error_trace=true. ServerError: Type: illegal_argument_exception Reason: "The difference between max_gram and min_gram in NGram Tokenizer must be less than or equal to: [1] but was [18]. This limit can be set by changing the [index.max_ngram_diff] index level setting."

您可以阅读有关此错误的更多信息here。

1. 没有像nGram_filter这样的过滤器，您需要将其更改为ngram

---

我通过检查 elasticsearch (localhost:9200/YOUR_INDEX_NAME/_mapping) 中的索引映射发现了这些问题，我发现未应用映射。第二步是查看DebugInformation 必须从索引创建响应中告诉我什么

var createIndexResponse = await client.Indices.CreateAsync("my_index1", ..);
createIndexResponse.DebugInformation

希望对您有所帮助。