[hibernate-dev] [SEARCH] Query-only analyzers with Elasticsearch - new annotation?

[Sanne Grinovero]

Hello,

I'm wondering how you'd all feel about the third solution:

 3. don't do it.

This depends of course how far it is blocking in practice. Maybe I'm
missing something, but couldn't a user simply use an additional
@AnalyzerDef, so that the analyzer definition is associated to a name,
and use that?

I guess that I'm missing why you'd want to force people to express
that a specific Analyzer is meant to be used only at query time
differently than one which is used at indexing time.
If there is need to clearly make such discrimination then this should
be made very clear to our users too, so I'd prefer if we could avoid
introducing new concepts for people to learn.. unless there's strong
need of course.

Is this issue relating to a specific user request?

Thanks,
Sanne



On 4 January 2017 at 16:00, Yoann Rodiere <yoann at hibernate.org> wrote:
> Hello team,
>
> I'm currently working on HSEARCH-2534, "Query-only analyzer definitions are
> never added to the index settings with Elasticsearch".
> This issue is about using analyzers only when querying with Elasticsearch.
> It is already possible with Lucene, but not in Elasticsearch, because we
> assume that any analyzer definition that is not referenced by a @Analyzer
> annotation is a Lucene analyzer [1].
>
> To be precise, the exact place where query-only analyzers are used is in
> EntityContext.overridesForField [2], and the overrides are leveraged even
> with Elasticsearch, for instance in ConnectedMultiFieldsTermQueryBuilder
> [3].
>
> I can see two solutions to the issue:
>
>    1. Make all analyzer definitions available for all indexing services.
>    2. Allow users to define, for each entity, which analyzer definitions
>    will be necessary when querying, even though the definitions are not used
>    when indexing.
>
> Solution 1 seems quite hard to implement correctly.
> First we'd have to have a different namespace for each indexing service,
> but I've already implemented that much.
> Second, some analyzer definitions are only valid for one indexing service,
> and not for the other.
> For instance, analyzer definitions using ElasticsearchTokenFilterFactory
> are specific to Elasticsearch. And Analyzer definitions using
> the WhitespaceTokenizerFactory with the "rule" parameter are only valid
> with embedded Lucene. And so on. To sum up, I'm not sure we can do
> something smart.
>
> Solution 2 is easier to implement, but requires to add a bit of API: the
> way for users to declare that a given analyzer definition is to be
> available when querying a given entity. I would add type-level
> @QueryAnalyzer(definition = "foo") and @QueryAnalyzers annotation.
>
> I know nobody wants to add new annotations in a minor, but right now that
> seems to be the only workable solution.
>
> What do you think?
>
> [1]
> https://github.com/hibernate/hibernate-search/blob/1847bd222128395056cdf6e7cfb601ceed5e40c3/engine/src/main/java/org/hibernate/search/engine/impl/ConfigContext.java#L277
> [2]
> https://github.com/hibernate/hibernate-search/blob/1847bd222128395056cdf6e7cfb601ceed5e40c3/engine/src/main/java/org/hibernate/search/query/dsl/EntityContext.java#L14
> [3]
> https://github.com/hibernate/hibernate-search/blob/1847bd222128395056cdf6e7cfb601ceed5e40c3/engine/src/main/java/org/hibernate/search/query/dsl/impl/ConnectedMultiFieldsTermQueryBuilder.java#L222
>
>
> Yoann Rodière <yoann at hibernate.org>
> Hibernate NoORM Team
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