JanusGraph can parallel read properties by vid?

[wen313]

for example：g.V().has('tag','janus').valueMap(true); if the tag of janus are many records,read properties by vid will be executed sequentially in backend,the time spent on network transmission will continue to accumulate..so can JanusGraph parallel read properties in the future?

[li-boxuan]

JanusGraph does support this. See query.batch option in https://docs.janusgraph.org/basics/configuration-reference/#query but whether it takes effect depends on the data backend you are using. For example, currently, Cassandra backend does not support it but HBase supports it. What is your data backend?

EDIT: just to update my answer to not mislead anyone who does not read the discussions below. In short, CQL backend supports "query.batch" option (see performance comparison between query.batch = false v.s. query.batch = true at https://www.experoinc.com/post/janusgraph-nuts-and-bolts-part-2-the-new-cql-adapter) but the option does not take effect on valueMap() step.

[wen313]

So if I use Scylladb backend，Is there a way to use parallel read properties by vid？

[li-boxuan]

So if I use Scylladb backend，Is there a way to use parallel read properties by vid？

At the moment you could use multi-threading at the application level.

Created an issue for this feature request: #2406

[li-boxuan]

See my latest comment on #2406 (comment). In short, using query.batch option in JanusGraph should satisfy your requirement.

[wen313]

but I find use query.batch is Invalid in valueMap query。

[li-boxuan]

@wen313 Yeah, I can confirm that optimization seems to be missing. It takes effect for values() but not valueMap(). Created #2444