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Re: Custom analyzer with traversal queries

Boxuan Li
 

Hi Flo,

Elasticsearch Index is only used when your query is a global query (a.k.a. graph-centric query in JanusGraph), i.e. look up vertices with conditions. `traversal.V().has(…)` is a global query.

On the other hand, `traversal().V(idx1, idx2, …).has(…)` is a vertex-centric query rather than global query. Elasticsearch is not involved, thus your custom analyzers are not used.

Your observations are valid. The documentation is not very clear indeed.

Unfortunately I don’t see any workaround here. Probably you could modify Text.java and build your own JanusGraph. You may also want to create a feature request to allow custom analyzers without indexing backends. Probably we could make Text.java pluggable (not sure if that’s possible).

Best regards,
Boxuan

On Jun 17, 2021, at 3:56 PM, florent@... wrote:

Hello everyone,


As it's my first post, I'd first thank you all for your work ! It has been pretty neat to discover all of the work !

We've started to investigate the use of custom analyzers in our schema (-> https://docs.janusgraph.org/v0.5/index-backend/field-mapping/#for-elasticsearch), where ES is used as an indexing backend.

From what I've seen, initial selections will indeed use the index (e.g. `traversal().V().has(...)`). However, it isn't always used, and sometimes the janusgraph implementation of the predicate is used (e.g. when `traversal().V(idx1, idx2, ...).has(...)`). In this latter case, it's the predicates as implemented here that are run. For text fields, it looks like a tokenization and lower-casing are perform by them directly.

I haven't seen mention of this case in the documentation. So, I'm wondering if my observations are valid.

If so, is there a way to force the usage of ES indices? An IDs query could be way to implement such feature (at least for ES).


All the best,
Flo

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