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Can the graph.set-vertex-id setting be changed

Rohit Jain <rohit.j...@...>
 

For the configuration setting graph.set-vertex-id, the documentation says:

Whether user provided vertex ids should be enabled and JanusGraph’s automatic id allocation be disabled. Useful when operating JanusGraph in concert with another storage system that assigns long ids but disables some of JanusGraph’s advanced features which can lead to inconsistent data. EXPERT FEATURE - USE WITH GREAT CARE.

However, it also says the mutability for this setting is FIXED.  If you try to set it in the CONF file, it says you should set it using the Management Interface.  When you try to change it there it says:

gremlin> mgmt.set('graph.set-vertex-id', true)
Cannot change the fixed configuration option: root.graph.set-vertex-id

So, which is it?  Can it be changed?  If it can, how?  If it cannot, then why even document it, or clearly say that it cannot be set, and for the error when setting it in the CONF file to stop saying use the management interface to set it.

Rohit
Robert Dale <rob...@...>
 


FIXED:  Once the database has been opened, these configuration options cannot be changed for the entire life of the database

You will need to start a clean database backend then janusgraph with the property enabled for the first time . Afterwards, the property will be ignored.

If you're using `./bin/janusgraph.sh start` then that means setting it in `conf/gremlin-server/janusgraph-cassandra-es-server.properties`


Robert Dale

On Thu, Aug 10, 2017 at 6:08 PM, Rohit Jain <rohit.j...@...> wrote:
For the configuration setting graph.set-vertex-id, the documentation says:

Whether user provided vertex ids should be enabled and JanusGraph’s automatic id allocation be disabled. Useful when operating JanusGraph in concert with another storage system that assigns long ids but disables some of JanusGraph’s advanced features which can lead to inconsistent data. EXPERT FEATURE - USE WITH GREAT CARE.

However, it also says the mutability for this setting is FIXED.  If you try to set it in the CONF file, it says you should set it using the Management Interface.  When you try to change it there it says:

gremlin> mgmt.set('graph.set-vertex-id', true)
Cannot change the fixed configuration option: root.graph.set-vertex-id

So, which is it?  Can it be changed?  If it can, how?  If it cannot, then why even document it, or clearly say that it cannot be set, and for the error when setting it in the CONF file to stop saying use the management interface to set it.

Rohit

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Rohit Jain <rohit.j...@...>
 

Thanks a lot Robert!  We should documents it somewhere as clearly as you articulated it!

Rohit
Rohit Jain <rohit.j...@...>
 

I do have a follow-up question.  Do the vertex ids have to be unique across all vertices?  I am assuming they do.  So, it is not like I can have vertex ids unique for within a label 'person' but not unique across other label's such as 'software'.  That is, I cannot have a 'person' vertex with id 1 and a 'software' vertex with id 1 as well.  In other words these are not ids unique for each entity / table as you would in a relational database sense, but a cross database id that would in essence have to be unique across all tables in that database.  If that is the case, they don't serve the purpose I had intended for them.

Rohit

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