Jerry  Hayes   Frank  Hardisty    (MGIS  Advisor)   

World  Data  Trends   •  Huge  increase  in  data     volume  in  recent  years.   •  Ninety  percent  of  world’s   data  has  been  generated  in   last  two  years.   •  Much  data  is  unstructured   and  exhibits  “rela>onships”   between  objects.   Source:  IDC   Data  Volume  (Exabytes)   Are  rela%onal  databases  the  best  architecture   to  meet  all  future  GIS  data  needs?   

Rela=onal  and  Graph  Databases   •  GIS  plaMorms  today  use  rela>onal  databases  for   storing  connected  network  data  .   Example  transporta%on  network   •  Should  GIS  plaMorms  begin  to  integrate  database   architectures?   

Physical    Model   Network  Model   •  A  network  model  is  a  directed  weighted  graph.     •  Physical  proper>es  are  abstracted  as  edge   costs.   •  Network  models  are  typically  in  tabular  format.   Typical  Connected  Network  Model   

Postgres  Network  Table   Simple  Network  Model  in  Postgres   •  A  row  represents  a  graph  {road}  edge  {segment}.   •  Each  edge  defines  a  “source”  and  “target”  node.   •  Costs  control  traversing  in  forward  and  reverse.   Implied  direc%on   

Traversing  Network  Models  using  SQL   •   Use  ‘WITH  RECURSIVE’  queries  in  Postgres   •  Deep  traversal  depths  are  prohibi>ve!   •  Performance  scales  poorly  with  graph  size!   Postgres  Recursive  SQL  Query   Postgres  Recursive  SQL  Performance   

Some  Open  Source  Alterna=ves  for  Traversing   Uses  Non-­‐Na=ve  Graph  Storage   Uses  Na=ve  Graph  Storage   •  Issues  to  consider  when  selec>ng  alterna>ve   o  Size  of  Dataset     o  Expected  Depth  of  Traversing   o  Number  of  concurrent  users   o  Degree  of  “connec>vity”   o  Complexity  of  rela>onships   

Storage  &  Build  Time  Comparisons   •  Hard  Drive  Storage  Advantage   o  pgRou>ng  was  an  order  of  magnitude  smaller.     Hard  Drive  Storage   •  Database  Build  Time  Advantage   o  Neo4j  was  much  faster.   Database  Build  Time   

Run=me  Memory  Usage  Comparisons     •  Concurrent  Users  Advantage     •  pgRou>ng  does  not  share  memory  between  threads.   •  Run>me  Memory  Advantage           •  pgRou>ng  reloads  en>re  dataset  for  each  traversal   pgRou=ng     Memory  History   Neo4j     Memory  History   

Traversal  Performance  Comparisons   •  Speed  vs  Dataset  Size  Advantage         •  Neo4j  is  constant  with  size…  pgRou>ng  degrades  with  size.   •  Traversal  Depth  Advantage    …    depends  on  applica>on.   •  For  deep  traversals  on  small  datasets       •  For  shallow  traversals  on  large  datasets       

Neo4j   Performance  Query  Sta=s=cs   Postgres   Cold  Cache   •  Neo4j  outperformed  Postgres  in  nearly  all  cases.   •  Cold  cache  observed  in  10%  of  Neo4j  queries.   •  Impact  of  Cold  Cache  was  moderate  to  severe.   

§  Connects  data  objects  on  the  Seman>c    Web.   §  Each  data  object  is  uniquely  iden>fied  with  URI.     Linked  Data  …  the  Next  Web  Fron=er   §  Links  describe  rela>onships  between  data.   §  Rela>onships  enable  automated  data  discovery.   Links   Data   §  Traversal  depths  are  typically  shallow.   

§     Server  side  is  stateless.   §   PostGIS  used  for  ..     •  Storing  physical  model.   •  Data  visualiza>on.     §     Neo4j  used  for  …   •  Storing  logical  model   •  Graph  traversals     Open  Source  System  Architecture   Implemented  in  the  IBM  Cloud!!!   

§   Provides  RESTful  API.   §  Enables  spa>al  analy>cs.   §  Enables  “data”  discovery.   §  Integrates  physical  and   logical  model  processing.   Implemented  in  the  IBM  Cloud!!!   Servlet  Architecture   

Applica=on  Demo