graphconnect 2014 sf: using a graph database to ensure a routable road network

MAP QA ANALYSIS WITH

/ Pieter Cailliau @cailliaup

ABOUT MEGraduated in Computer Science

Master thesis: Time based graph model for a dynamic routeplanner

Started @TomTom in 2010

Unfortunately, I'm to not related Robert Cailliau

ABOUT

PRODUCTS OF

CONSUMER

AUTOMOTIVE

LICENSING

TELEMATICS

MAP EDITING PROCESS

EXAMPLE QA CHECKS

OUR MOST EXPENSIVE QA CHECKS

A Restricted Access Island (RAI) is a piece of theRoad Network where you can navigate locally

but not reach or leave globally.

THE RAI ALGORITHM

ROAD CATEGORIES

If you travel from A to B, a route exists that willget you to your destination B in a strict

ascending order of road categories followed by astrict descending order of road categories to B

THIS IS NOT A RAI!

THIS IS A RAI!

It is sufficient to know when changing a road X,with RC(X)=i, that we can still reach* a road Y,

with RC(Y)>i, without going over a lowerRC.**/***

* reach means that we take all trafic restricitons into account.** this transitivity works on condition that the highest road category is connected.

*** the inverse is also needed, from a higher RC towards road X.

BREADTH FIRST SEARCH

RAI CHECK FACTS

GRAPH DENSITY

RDBMSOptimized for all our data

geospatial index

Average QA time = 40sec

Depth limitation of 100, 97% of violations found

New violations are added to our database

RDBMS + NEO4JOptimized for routing/navigation

Average QA time = 5.2sec

No depth limitation

All RAI violations detected

NEO4J IMPLEMENTATION DETAILSEmbedded

High Availability

Semantic layer on top of it

Algorithms in java

Our graph model

LESSONS LEARNED

IT’S HARD TO MAINTAIN MULTIPLE “MATERIALIZED VIEWS”OF OUR DATABASE

BRING YOUR CODE TO THE DATA

WHAT'S NEXT?Migrate more QA Checks to Neo4J

Crawling agents

DEMO!

QUESTIONS?