Using indexes

The graph traversal shown uses an index used discover a certain person vertices to start the query:

g.V().has('person', 'name', 'Emeril LAGASSE').out('created').values('name')

results in:

==>Wild Mushroom Stroganoff
==>Spicy Meatloaf

Checking for the use of indexing can be accomplished with the profile() method:

g.V().has('person', 'name', 'Emeril LAGASSE').out('created').values('name').profile()

with the detailed information:

==>Traversal Metrics
Step                                                               Count  Traversers       Time (ms)    % Dur
=============================================================================================================
__.V().hasLabel("person").has("name","Emeril LA...                     1           1          27.935    78.56
  CQL statements ordered by overall duration                                                  24.137
    \_1=SELECT * FROM food.person WHERE solr_query = '{"q":"*:*", "fq":["name:Emeril\\ LAGASSE"]}' LIMIT 2147
        483647 / Duration: 24 ms / Count: 1
HasStep([~label.eq(person), name.eq(Emeril LAGA...                     1           1           0.399     1.12
__.out().hasLabel("created")                                           2           2           6.161    17.33
  CQL statements ordered by overall duration                                                   3.369
    \_1=SELECT * FROM food.person__created__recipe WHERE person_person_id = ? / Duration: 2 ms / Count: 1 / I
        ndex type: Table: person__created__recipe
    \_2=SELECT * FROM food.recipe WHERE recipe_id = ? / Duration: 1 ms / Count: 2 / Index type: Table: recipe
PropertiesStep([name],value)                                           2           2           0.624     1.76
NoOpBarrierStep(2500)                                                  2           2           0.190     0.53
ReferenceElementStep                                                   2           2           0.248     0.70
                                            >TOTAL                     -           -          35.559        -

The first CQL statement uses a search index WHERE solr_query = '{"q":"*:*", "fq":["name:Emeril\\ LAGASSE"]}' to first find the person, then uses two CQL statements to find the recipes that are adjacent to that particular person vertex. Finally, the recipe names are retrieved.

An index on an edge property can narrow the query, such as this one that finds all the outgoing edges for reviews that John DOE wrote that have a rating of greater or equal to 3 stars:

g.V().has('person','name','John DOE').outE().has('stars', gte(3))

results in:

==>e[dseg:/person-reviewed-recipe/46ad98ac-f5c9-4411-815a-f81b3b667921/2005][dseg:/person/46ad98ac-f5c9-4411-815a-f81b3b667921-reviewed->dseg:/recipe/2005]
==>e[dseg:/person-reviewed-recipe/46ad98ac-f5c9-4411-815a-f81b3b667921/2001][dseg:/person/46ad98ac-f5c9-4411-815a-f81b3b667921-reviewed->dseg:/recipe/2001]

Using profile() on the query shows that a search index query was used in the initial step, and the output shown here shows that in the second step, the person__reviewed__recipe_by_person_person_id_stars materialized view index was used to cut the latency of the query:

g.V().has('person','name','John DOE').outE().has('stars', gte(3)).profile()

with the detailed information:

==>Traversal Metrics
Step                                                               Count  Traversers       Time (ms)    % Dur
=============================================================================================================
__.V().hasLabel("person").has("name","John DOE")                       1           1          13.626    87.00
  CQL statements ordered by overall duration                                                  12.376
    \_1=SELECT * FROM food.person WHERE solr_query = '{"q":"*:*", "fq":["name:John\\ DOE"]}' LIMIT 2147483647
         / Duration: 12 ms / Count: 1
HasStep([~label.eq(person), name.eq(John DOE)])                        1           1           0.110     0.70
__.outE().has("stars",P.gte((int) 3))                                  2           2           1.589    10.15
  CQL statements ordered by overall duration                                                   0.573
    \_1=SELECT * FROM food.person__reviewed__recipe_by_person_person_id_stars WHERE person_person_id = ? AND
        stars >= ? / Duration: < 1 ms / Count: 1 / Index type: Materialized view
HasStep([stars.gte(3)])                                                2           2           0.177     1.14
ReferenceElementStep                                                   2           2           0.158     1.01
                                            >TOTAL                     -           -          15.662        -

There are cases, such as a query that requires both a search predicate and a map index to work, where the usual querying fails. For instance, the following query will fail:

g.V().
  hasLabel('person').has('name', 'John DOE').
  has('badge', containsValue('2016-01-01' as LocalDate)).
  values('name')

results in:

One or more indexes are required to execute the traversal: g.V().hasLabel("person").has("name","John DOE").has("badge",containsValue(java.time.LocalDate.of(2016, 1, 1))).values("name")
Failed step: __.V().hasLabel("person").has("badge",containsValue(java.time.LocalDate.of(2016, 1, 1))).has("name","John DOE")
CQL execution: No table or view could satisfy the query 'SELECT * FROM food.person WHERE badge CONTAINS ? AND name = ?'
'schema.indexFor(<your_traversal>).analyze()' can't suggest any indexes to create as some steps in your traversal are not supported yet.

Alternatively consider using:
g.with('ignore-unindexed') to ignore unindexed traversal. Your results may be incomplete.
g.with('allow-filtering') to allow filtering. This may have performance implications.

Since search indexes cannot index map collections, this query cannot be completed as presented. However, using a mid-traversal query can identify whether or not John DOE does have a badge that meets the requirements:

g.V().has('person','name', 'John DOE').as('a').
  V().has('person','badge', containsValue('2016-01-01' as LocalDate)).as('b').
  select('a','b').
    by('name').by('badge')

results in:

==>{a=John DOE, b={gold=2017-01-01, silver=2016-01-01}}

This is an interesting query that takes advantage of using both a search index and a secondary index to complete the traversal using a mid-traversal V()step:

g.V().has('person','name', 'John DOE').as('a').
  V().has('person','badge', containsValue('2016-01-01' as LocalDate)).as('b').
  select('a','b').
    by('name').by('badge').
  profile()

results in:

==>Traversal Metrics
Step                                                               Count  Traversers       Time (ms)    % Dur
=============================================================================================================
__.V().hasLabel("person").has("name","John DOE")                       1           1          12.464    73.33
  CQL statements ordered by overall duration                                                  10.958
    \_1=SELECT * FROM food.person WHERE solr_query = '{"q":"*:*", "fq":["name:John\\ DOE"]}' LIMIT 2147483647
         / Duration: 10 ms / Count: 1
HasStep([~label.eq(person), name.eq(John DOE)])...                     1           1           0.174     1.02
__.V().hasLabel("person").has("badge",containsV...                     1           1           3.402    20.02
  CQL statements ordered by overall duration                                                   2.339
    \_1=SELECT * FROM food.person WHERE badge CONTAINS ? / Duration: 2 ms / Count: 1 / Index type: Secondary
        index
HasStep([~label.eq(person), badge.containsValue...                     1           1           0.573     3.38
SelectStep(last,[a, b],[value(name), value(badg...                     1           1           0.100     0.59
ReferenceElementStep                                                   1           1           0.282     1.66
                                            >TOTAL                     -           -          16.997