JanusGraph•3mo ago

Indexes are not being used even after enabling

I have setup one composite index, one mixed index and one relation index. Although all of them have the 'ENABLED' status, the queries are still doing a full scan. I have attached the schema. Here is the query that I am trying to execute:

gremlin> g.V().has('_id', '66b0dc9f2bd5e4709894fc29').profile()
==>Traversal Metrics
Step                                                               Count  Traversers       Time (ms)    % Dur
=============================================================================================================
JanusGraphStep([],[_id.eq(66b0dc9f2bd5e4709894f...                     1           1         101.875   100.00
  constructGraphCentricQuery                                                                   0.103
  constructGraphCentricQuery                                                                   0.017
  GraphCentricQuery                                                                          101.534
    \_condition=(_id = 66b0dc9f2bd5e4709894fc29)
    \_orders=[]
    \_isFitted=false
    \_isOrdered=true
    \_query=[]
    scan                                                                                     101.341
      \_query=[]
      \_fullscan=true
      \_condition=VERTEX
                                            >TOTAL                     -           -         101.875        -

gremlin> g.V().has('_id', '66b0dc9f2bd5e4709894fc29').profile()
==>Traversal Metrics
Step                                                               Count  Traversers       Time (ms)    % Dur
=============================================================================================================
JanusGraphStep([],[_id.eq(66b0dc9f2bd5e4709894f...                     1           1         101.875   100.00
  constructGraphCentricQuery                                                                   0.103
  constructGraphCentricQuery                                                                   0.017
  GraphCentricQuery                                                                          101.534
    \_condition=(_id = 66b0dc9f2bd5e4709894fc29)
    \_orders=[]
    \_isFitted=false
    \_isOrdered=true
    \_query=[]
    scan                                                                                     101.341
      \_query=[]
      \_fullscan=true
      \_condition=VERTEX
                                            >TOTAL                     -           -         101.875        -

message.txt

Solution:

Your index byIdTypeAndName includes 3 property keys: _id, type, and name. In that case, you also have to use all 3 property keys in your traversal for the index to work

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7 Replies

paull8147•3mo ago

hello, you need to precise the label of the vertex g.V().hasLabel("myLabel").has('_id', '66b0dc9f2bd5e4709894fc29').profile() OR g.V().has("myLabel", '_id', '66b0dc9f2bd5e4709894fc29').profile()

karthikrajuOP•3mo ago

Tried adding the label but still no luck. The profile response still shows fullScan=true

Solution

Florian Hockmann•3mo ago

Your index byIdTypeAndName includes 3 property keys: _id, type, and name. In that case, you also have to use all 3 property keys in your traversal for the index to work

Florian Hockmann•3mo ago

https://docs.janusgraph.org/schema/index-management/index-performance/#composite-index

Note, that all keys of a composite graph index must be found in the query’s equality conditions for this index to be used. For example, the following query cannot be answered with either of the indexes because it only contains a constraint on age but not name. g.V().has('age', 30)

karthikrajuOP•3mo ago

Yes, that was the problem. Completely overlooked that. Thank you!

karthikrajuOP•3mo ago

The reason for adding the 'type' key was that janusgraph doesn't index labels as discussed in this github issue: https://github.com/JanusGraph/janusgraph/issues/283 I like the readability of having queries like: g.V().has('<label>', '<property'>, '<value>') but with the type property all the queries will look like this: g.V().has('<type>').has('_id', '<value>') I would like to know if the queries still use the indexes if I just create a composite index for the _id and have queries like g.V().has('<label>', '_id', '<value>')

GitHub

Index by label · Issue #283 · JanusGraph/janusgraph

In Janus I can create a composite index for a single property. Why then can I not create a composite index for a vertex label without a property? My use case is that we're using vertex labels t...

karthikrajuOP•3mo ago

Update: Having a single composite index for _id and using the query: g.V().has('<label>', '_id', '<value>') still uses the index

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Indexes are not being used even after enabling