Janusgraph: Document, and possibly improve, how to list existing indexes

[chupman]

I wasn't able to find how to list existing indexes (or indices) in the docs.

The command is currently mgmt.getGraphIndexes(Vertex.class) although I'm not sure if vertex-centric would show up under mgmt.getGraphIndexes(Edge.class) instead.

In addition to documentation I think it would be great if we created a getGraphIndexes() method that took no parameters and gave a list of all the indexes and their current state.

[pluradj]

I'll point out the wiki page on indexing. It would make sense to pull a lot of that into the main documentation.

Adding @robertdale 's schema describe script more formally into the Gremlin Console could be interesting too, but I'd put that in a separate issue.

The idea for a generic getGraphIndexes() sounds interesting, but from a Java interface perspective, it would be more difficult.

There is no getIndexStatus() method on the base interface Index interface, and the signature is different between JanusGraphIndex.getIndexStatus(PropertyKey) and RelationTypeIndex.getIndexStatus().

[chupman]

Thanks for the link to @robertdale 's schema describe script. My real goal was easier to use administrative commands to gather schema information. I just started on a getGraphSchema() method for the management API using schema describe as a reference.

Also you're 100% correct about the other approaches being more work so I'm ultimately taking the path of least resistance 💯

[chupman]

I still need to add tests and do some work to make each section formatted correctly when separately called, but I finished a first pass. Right now I'm working with a width of 100 characters. I'd really like to get it to 80, but it's a bit of a challenge. If anyone has a really strong feeling about it I can shrink the first column from 30 to 15 and abbreviate some headers to get the other 5.

gremlin> mgmt.printGraphSchema()
==>------------------------------------------------------------------------------------------------
Vertex Label Name              | Partitioned | Static                                             |
---------------------------------------------------------------------------------------------------
titan                          | false       | false                                              |
location                       | false       | false                                              |
god                            | false       | false                                              |
demigod                        | false       | false                                              |
human                          | false       | false                                              |
monster                        | false       | false                                              |
---------------------------------------------------------------------------------------------------
Edge Label Name                | Directed    | Unidirected | Multiplicity                         |
---------------------------------------------------------------------------------------------------
brother                        | true        | false       | MULTI                                |
father                         | true        | false       | MANY2ONE                             |
mother                         | true        | false       | MANY2ONE                             |
battled                        | true        | false       | MULTI                                |
lives                          | true        | false       | MULTI                                |
pet                            | true        | false       | MULTI                                |
---------------------------------------------------------------------------------------------------
Property Key Name              | Cardinality | Data Type                                          |
---------------------------------------------------------------------------------------------------
name                           | SINGLE      | class java.lang.String                             |
age                            | SINGLE      | class java.lang.Integer                            |
time                           | SINGLE      | class java.lang.Integer                            |
reason                         | SINGLE      | class java.lang.String                             |
place                          | SINGLE      | class org.janusgraph.core.attribute.Geoshape       |
---------------------------------------------------------------------------------------------------
Vertex Index Name              | Type        | Unique    | Backing        | Key:           Status |
---------------------------------------------------------------------------------------------------
name                           | Composite   | true      | internalindex  | name:         ENABLED |
vertices                       | Mixed       | false     | search         | age:          ENABLED |
---------------------------------------------------------------------------------------------------
Edge Index (VCI) Name          | Type        | Unique    | Backing        | Key:           Status |
---------------------------------------------------------------------------------------------------
edges                          | Mixed       | false     | search         | reason:       ENABLED |
                               |             |           |                | place:        ENABLED |
---------------------------------------------------------------------------------------------------
Relation Index                 | Type        | Direction | Sort Key       | Order    |     Status |
---------------------------------------------------------------------------------------------------
battlesByTime                  | battled     | BOTH      | time           | decr     |    ENABLED |
---------------------------------------------------------------------------------------------------

[FlorianHockmann]

That looks really great, @chupman. Would it be possible to also include the schema constraints in this output?

[chupman]

@FlorianHockmann I'm targeted at 0.2.3 right now, but already planning to add it once it's merged to master.

[chupman]

printSchema has been merged to master, still need to add schema constraints section in master though.

[cmilowka]

as requested by "hadoopmarc" I am adding the following comments for consideration:

Global indexes (Composite,Mixed) can be limited to the "constraint" by indexOnly() step, from JanusGraph documentation:
mgmt.buildIndex('byNameAndLabel', Vertex.class).addKey(name).indexOnly(god).buildCompositeIndex()

We should also learn how the index was created from JanusGraphIndex instance, but the method to get IndexOnly() is not there, ...how to know it was limited to just "god" labels. I guess knowledge is there, because JG should is able to "reindex" just by the "name" of the index, repeating creation method entirely.
Regards, CM

[cmilowka]

BO XUAN LIFeb said: "You can do this:
JanusGraphSchemaType constraint = ManagementSystem.getGraphIndexDirect("indexName", ((ManagementSystem) mgmt).getWrappedTx()).getSchemaTypeConstraint();
and that works, could be wrapped in some kind of JanusGraphIndex method, like getIndexedOnlyBy()