1. Running Neo4j in Production
Tips, Tricks and Optimizations

2. This Talk...
● How we scaled our prod graph
● Challenges faced doing this
● Various lessons we learned and techniques
we used
● Some stuff I’m looking forward to in Neo4j

3. SNAP Interactive
● Presented by David Fox (Big Data Engineer)
● Social dating app AYI (Are You Interested?)
● Friends and interests

4. How We Use Neo4j
● Model the friend data of our millions of users
● Indicate connections everywhere on app
● 1.1+ billion nodes
● 8.5+ billion relationships
● 450gb+ store
● 3 instance cluster

5. Importing lots of data
● Find the right tool
o First try normal Cypher
o No good? Bring out the big guns - Java Batch
Inserter
● Java Batch Inserter
o Sort relationships (GNU sort)
o Try to keep index lookups to in-memory lookups only
 Giant HashMap!

6. But wait!!!
● Cypher CSV import
o 2.1 M01
o Supposed to be good for importing large data sets
o Anyone tried it?

7. Read Querying
● Always try Cypher first
o Performance is being improved
● How can you tell if performance is where you
need it to be?
o Time queries (cold vs. warm cache)
o Load testing!

8. Read Querying cont.
● Dark querying
o Great for benchmarking system where Neo4j
functionality is being injected
o Mitigates risk
o Provides results that are very close to real world
patterns

9. Read Querying cont.
● Reads too slow? Try these things.
o Write high-throughput business-critical queries in
Java
 unmanaged extension
 faster
 hard limits
o Cache shard
 country, age, gender, etc.
 you hit warm cache more often

10. Read Querying cont.
● Warm the cache!
o Touch all the nodes
o Touch all the relationships

11. Writing
● Decide which writes need to be synchronous
and which can be asynchronous
● Queue up asynchronous writes (routine
updates, non-vital to immediate user-
experience)
o Try to evenly distribute them
o How do we do this? Baserunner!

12. Baserunner
● Written by SNAP developer
● Walks userbase randomly instead of
sequentially
o This avoids pockets of heavily increased write
queries
o Allows us to do high-velocity updating of our data

13. Tuning the JVM
● For a really high-throughput environment,
G1 GC has been very helpful
o Good at adapting itself
o We experienced less system-stopping pauses than
with CMS
o Try CMS first but remember G1 as option

14. Hardware is Important
● Lots of memory
● Working set too big for memory?
o SSDs are helpful
o Optimization techniques discussed become much
more important

15. Not Everything is Your Fault!
● Like any software, Neo4j has bugs
● Developers are receptive
● File reports on Github when you find issues

16. Some stuff to look forward to...
● Relationship grouping (2.1 M01)
o helps mitigate the super node/dense node problem
● Ronja (rewrite of the Cypher query
language, 2.1?)
● More flexible label index searching (after
2.1)

17. Questions?