Scaling with Postgres (Robert Treat)

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Scaling with Postgres (Robert Treat)

  1. 1. Scaling with Postgres Robert Treat Highload++ 2010Monday, October 25, 2010
  2. 2. Who Am I? ✤ Robert Treat ✤ OmniTI ✤ Design, Development, Database, OpsMonday, October 25, 2010
  3. 3. Who Am I? ✤ Robert Treat ✤ OmniTI ✤ Design, Development, DATABASE, OpsMonday, October 25, 2010
  4. 4. Who Am I? ✤ Robert Treat ✤ OmniTI ✤ Design, Development, DATABASE, Ops ✤ Etsy, Allisports, National Geographic, Gilt, etc...Monday, October 25, 2010
  5. 5. Who Am I? ✤ Robert Treat ✤ Postgres ✤ Web, Advocacy, phpPgAdmin ✤ Major ContributorMonday, October 25, 2010
  6. 6. Who Am I? ✤ Postgres 6.5 -> 9.1alpha1 ✤ Terabytes of data ✤ Millions of transactions per day ✤ OLTP, ODS, DW ✤ Perl, PHP, Java, Ruby, C#Monday, October 25, 2010
  7. 7. Who Am I? OBSERVATION == LEARNING (hopefully)Monday, October 25, 2010
  8. 8. Scalability It is the ability of a computer application or product (hardware or software) to continue to function well when it (or its context) is changed in size or volume in order to meet a user need.Monday, October 25, 2010
  9. 9. Scalability Given ever increasing loadMonday, October 25, 2010
  10. 10. Scalability Given ever increasing load NEVER GO DOWN ALWAYS PERFORM WELLMonday, October 25, 2010
  11. 11. Scalability Given ever increasing load NEVER GO DOWN ALWAYS PERFORM WELL impossible goal, but we’ll tryMonday, October 25, 2010
  12. 12. Scalability Given ever increasing load NEVER GO DOWN ALWAYS PERFORM WELL NOTE! data loss is not a goal, but ideally we won’t lose it :-)Monday, October 25, 2010
  13. 13. It starts with culture...Monday, October 25, 2010
  14. 14. ✤ Get over schema purity ✤ add column default not nullMonday, October 25, 2010
  15. 15. ✤ Get over schema purity ✤ add column default not null Good performance comes from good schema design, HOWEVER, perfect relational modeling is NOT THE GOALMonday, October 25, 2010
  16. 16. ✤ Devs must own schema and queries ✤ they design, you refineMonday, October 25, 2010
  17. 17. ✤ Devs must own schema and queries ✤ they design, you refine Performance and scalability cannot be managed solely within the database; both require application level knowledge. To achieve this, application developers need to have visibility of the resources they work onMonday, October 25, 2010
  18. 18. Gain VisibilityMonday, October 25, 2010
  19. 19. Gain Visibility ✤ Monitoring ✤ Alerts ✤ Trending ✤ Capacity Planning ✤ Performance TuningMonday, October 25, 2010
  20. 20. Gain Visibility ✤ Alerts ✤ server: out of disk space, high load, etc... ✤ database: connections, sequences, etc... ✤ business: registrations, revenue, etc... ✤ etc... check_postgres.plMonday, October 25, 2010
  21. 21. Gain Visibility ✤ Trending ✤ server: disk usage, load, etc... ✤ database: connections, sequences, etc... ✤ business: registrations, revenue, etc... ✤ etc... cacti, mrtg, circonusMonday, October 25, 2010
  22. 22. Gain Visibility ✤ Capacity Planning ✤ disks, cpu, memory ✤ connections, vacuum, bloat simple projections, done regularly, are good enoughMonday, October 25, 2010
  23. 23. Gain Visibility ✤ Performance tuning ✤ how long do queries take? ✤ how often do they run? pgfouineMonday, October 25, 2010
  24. 24. Gain Visibility COMMITS/PUSHESMonday, October 25, 2010
  25. 25. Gain Visibility ALL alerts, graphs, query reports, etc... MUST be available to EVERYONE on the team AT ALL TIMESMonday, October 25, 2010
  26. 26. Hands on You can’t succeed without first putting the right culture in place. Once you are on the right path, make sure you have the right technologyMonday, October 25, 2010
  27. 27. Postgres Versions ✤ MINIMUM: 8.3 ✤ removes xid for read only queries, significant reduction in vacuum activityMonday, October 25, 2010
  28. 28. Postgres Versions ✤ MINIMUM: 8.3 ✤ removes xid for read only queries, significant reduction in vacuum activity seriously!Monday, October 25, 2010
  29. 29. Postgres Versions ✤ MINIMUM: 8.3 ✤ removes xid for read only queries, significant reduction in vacuum activity ✤ BETTER: 8.4 ✤ revised free space map management leads to more efficient vacuumingMonday, October 25, 2010
  30. 30. Postgres Versions ✤ MINIMUM: 8.3 ✤ removes xid for read only queries, significant reduction in vacuum activity ✤ BETTER: 8.4 ✤ revised free space map management leads to more efficient vacuuming ✤ WHY NOT? 9.0 ✤ Hot standby / streaming replication couldn’t hurtMonday, October 25, 2010
  31. 31. Speaking of replication ✤ Common practice for scaling websites ✤ Good for READ based loads ✤ We have used many: ✤ slony, rubyrep, bucardo, 9.0 built-in, mammoth, wrote-our-ownMonday, October 25, 2010
  32. 32. Speaking of replicationMonday, October 25, 2010
  33. 33. Speaking of replication ✤ No favorite system for this, evaluate based on: ✤ avoid solutions that duplicate writes at sql level (imho) ✤ how comfortable am I debugging the system? ✤ do you need automated schema changes? ✤ how much redundancy / complexity do you need? ✤ how does the system handle node failure for N nodes?Monday, October 25, 2010
  34. 34. So what would you use? (tm) ✤ 2 Nodes, master + standby: Postgres 9.0 ✤ Master + multiple slaves: Slony ✤ Master-Master: Bucardo All choices subject to change!!Monday, October 25, 2010
  35. 35. A word about “Sharding” ✤ Distributed computing is hard(er) ✤ we think of things in a singular global state ✤ the more we can work in that model, the better ✤ RDBM offer poor solutions for multiple masters ✤ you must manage that complexity on your ownMonday, October 25, 2010
  36. 36. A word about “Sharding” ✤ Splitting systems by service: ✤ separate db for login, forums, sales, etc... ✤ allows for growth ✤ provides simple interfaceMonday, October 25, 2010
  37. 37. Pooling ✤ Postgres connections are expensive! ✤ fork new process per connection ✤ keep 1 process open per connection ✤ 1000+ processes you will notice troubleMonday, October 25, 2010
  38. 38. Pooling ✤ Postgres connections are expensive! ✤ fork new process per connection ✤ keep 1 process open per connection ✤ 1000+ processes you will notice trouble ✤ POOLING ✤ JDBC, mod-perl ✤ pgbouncer ftw!Monday, October 25, 2010
  39. 39. Summary ✤ Schema / Queries should be shared between dev, dba teams! ✤ Monitoring + Visibility! ✤ >= 8.3 Required! ✤ Replication, jump in it! ✤ Use connection pooling!Monday, October 25, 2010
  40. 40. Thanks! Oleg & Crew Highload++ OmniTI Postgres Community! You! more: @robtreat2 www.xzilla.netMonday, October 25, 2010

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