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- 2. INTRODUCTION Bartosz Sypytkowski ▪ @Horusiath ▪ b.sypytkowski@gmail.com ▪ bartoszsypytkowski.com
- 3. What’s the problem? Opertional Transfromations Replicated Growable Arrays How do we replicate? How to optimize this thing? How to collect garbage? AGENDA
- 6. PROBLEM Alice Bob CONTINOUS ins(5, U) CONTINUOUS CONTINOUS ins(8, ?) CONTINOUS?
- 7. PROBLEM Alice Bob CONTINOUS ins(5, U) CONTINUOUS CONTINOUS ins(8, ?) CONTINOUS? ins(5, U)
- 8. PROBLEM Alice Bob CONTINOUS ins(5, U) CONTINUOUS CONTINOUS ins(8, ?) CONTINOUS? CONTINUOUS? ins(5, U)
- 9. PROBLEM Alice Bob CONTINOUS ins(5, U) CONTINUOUS CONTINOUS ins(8, ?) CONTINOUS? ins(8, ?) CONTINUOUS? ins(5, U)
- 10. PROBLEM Alice Bob CONTINOUS ins(5, U) CONTINUOUS CONTINOUS ins(8, ?) CONTINOUS? CONTINUOU?S ins(8, ?) CONTINUOUS? ins(5, U)
- 11. PROBLEM Alice Bob CONTINOUS ins(5, U) CONTINUOUS CONTINOUS ins(8, ?) CONTINOUS? CONTINUOU?S ins(8, ?) CONTINUOUS? ins(5, U)
- 12. WHY NOT JUST USE CENTRAL DATABASE ? 1. A single contributor can issue hundreds of ops/min. 2. Lag cannot be visible for a naked eye. 3. We should accept periodic disconnections, the longer the better. 4. … and maybe push the cost to the edges?
- 13. OPERATIONAL TRANSFORMATION As seen in Google Docs, Apache Wave and Etherpad
- 14. OPERATIONAL TRANSFORMATION Alice Bob C O N T I N O U S C O N T I N O U S
- 15. OPERATIONAL TRANSFORMATION Alice Bob C O N T I N O U S ins(6, U, A) C O N T I N O U S ins(9, ?, B)
- 16. OPERATIONAL TRANSFORMATION Alice Bob C O N T I N O U S ins(6, U, A) C O N T I N U O U S +1 +1 +1 +1 +1 C O N T I N O U S ins(9, ?, B) C O N T I N O U S ? +1 +1
- 17. OPERATIONAL TRANSFORMATION Alice Bob C O N T I N O U S ins(6, U, A) C O N T I N U O U S +1 +1 +1 +1 +1 C O N T I N O U S ins(9, ?, B) C O N T I N O U S ? +1 +1 ins(9, ?, B) C O N T I N U O U S +1 +1 +1 +1 +1
- 18. OPERATIONAL TRANSFORMATION Alice Bob C O N T I N O U S ins(6, U, A) C O N T I N U O U S +1 +1 +1 +1 +1 C O N T I N O U S ins(9, ?, B) C O N T I N O U S ? +1 +1 C O N T I N U O U S ? ins(9, ?, B) +1 +1 +1 +1 +1 +1 +1 +1
- 19. OPERATIONAL TRANSFORMATION Alice Bob C O N T I N O U S ins(6, U, A) C O N T I N U O U S +1 +1 +1 +1 +1 C O N T I N O U S ins(9, ?, B) C O N T I N O U S ? +1 +1 C O N T I N U O U S ? ins(6, U, A)ins(9, ?, B) +1 +1 +1 +1 +1 +1 +1 +1 C O N T I N O U S ? +1 +1
- 20. OPERATIONAL TRANSFORMATION Alice Bob C O N T I N O U S ins(6, U, A) C O N T I N U O U S +1 +1 +1 +1 +1 C O N T I N O U S ins(9, ?, B) C O N T I N O U S ? +1 +1 C O N T I N U O U S ? C O N T I N U O U S ? ins(6, U, A)ins(9, ?, B) +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1
- 21. “Unfortunately, implementing OT sucks” PROBLEM WITH OPERATIONAL TRANSFORMATION - Joseph Gentle (Google Wave, ShareJS)
- 23. WE NEED IMMUTABLE INDEXES 1:AABSOLUTE INDEX ID UNIQUE REPLICA ID
- 24. REPLICATED GROWABLE ARRAY Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A
- 25. REPLICATED GROWABLE ARRAY Alice Bob C O N T I N O U S ins(6A, U, 10A) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S ins(9A, ?, 10B) 1A 2A 3A 4A 5A 6A 7A 8A 9A
- 26. REPLICATED GROWABLE ARRAY Alice Bob C O N T I N O U S ins(6A, U, 10A) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S ins(9A, ?, 10B) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S ? 1A 2A 3A 4A 5A 6A 7A 8A 9A 10B
- 27. REPLICATED GROWABLE ARRAY Alice Bob C O N T I N O U S ins(6A, U, 10A) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S ins(9A, ?, 10B) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S ? 1A 2A 3A 4A 5A 6A 7A 8A 9A 10B ins(9A, ?, 10B)
- 28. REPLICATED GROWABLE ARRAY Alice Bob C O N T I N O U S ins(6A, U, 10A) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S ins(9A, ?, 10B) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S ? 1A 2A 3A 4A 5A 6A 7A 8A 9A 10B C O N T I N U O U S ? 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A 10B ins(9A, ?, 10B)
- 29. REPLICATED GROWABLE ARRAY Alice Bob C O N T I N O U S ins(6A, U, 10A) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S ins(9A, ?, 10B) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S ? 1A 2A 3A 4A 5A 6A 7A 8A 9A 10B C O N T I N U O U S ? 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A 10B ins(6A, U, 10A)ins(9A, ?, 10B)
- 30. REPLICATED GROWABLE ARRAY Alice Bob C O N T I N O U S ins(6A, U, 10A) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S ins(9A, ?, 10B) 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S ? 1A 2A 3A 4A 5A 6A 7A 8A 9A 10B C O N T I N U O U S ? 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A 10B C O N T I N U O U S ? 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A 10B ins(6A, U, 10A)ins(9A, ?, 10B)
- 31. HOW TO INSERT AT THE SAME POSITION?
- 32. HOW TO INSERT AT THE SAME POSITION? 6A < 6B MAKE POSITIONS COMPARABLE
- 33. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A
- 34. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B)
- 35. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B)
- 36. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B) ins(6A, N, 10B)
- 37. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B) ins(6A, N, 10B) 10B > 10A
- 38. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A C O N T I N N U O U S 1A 2A 3A 4A 5A 6A 10B 10A 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B) ins(6A, N, 10B)
- 39. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A C O N T I N N U O U S 1A 2A 3A 4A 5A 6A 10B 10A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B) ins(6A, N, 10B) ins(6A, U, 10A)
- 40. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A C O N T I N N U O U S 1A 2A 3A 4A 5A 6A 10B 10A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B) ins(6A, N, 10B) ins(6A, U, 10A) 10A < 10B
- 41. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A C O N T I N N U O U S 1A 2A 3A 4A 5A 6A 10B 10A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B) ins(6A, N, 10B) ins(6A, U, 10A) 10A > 7A
- 42. REPLICATED GROWABLE ARRAY INSERT AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N N O U S 1A 2A 3A 4A 5A 6A 10B 7A 8A 9A C O N T I N N U O U S 1A 2A 3A 4A 5A 6A 10B 10A 7A 8A 9A C O N T I N N U O U S 1A 2A 3A 4A 5A 6A 10B 10A 7A 8A 9A ins(6A, U, 10A) ins(6A, N, 10B) ins(6A, N, 10B) ins(6A, U, 10A)
- 43. HOW TO INSERT AND DELETE AT THE SAME POSITION?
- 44. HOW TO INSERT AND DELETE AT THE SAME POSITION? TOMBSTONES
- 45. REPLICATED GROWABLE ARRAY INSERT AND DELETE AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A
- 46. REPLICATED GROWABLE ARRAY INSERT AND DELETE AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A ins(6A, U, 10A) del(6A)
- 47. REPLICATED GROWABLE ARRAY INSERT AND DELETE AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A ins(6A, U, 10A) del(6A)
- 48. REPLICATED GROWABLE ARRAY INSERT AND DELETE AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A ins(6A, U, 10A) del(6A) del(6A)
- 49. REPLICATED GROWABLE ARRAY INSERT AND DELETE AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A ins(6A, U, 10A) del(6A) del(6A)
- 50. REPLICATED GROWABLE ARRAY INSERT AND DELETE AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A ins(6A, U, 10A) del(6A) ins(6A, U, 10A)del(6A)
- 51. REPLICATED GROWABLE ARRAY INSERT AND DELETE AT THE SAME POSITION Alice Bob C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I N U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A C O N T I N O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I O U S 1A 2A 3A 4A 5A 6A 7A 8A 9A C O N T I U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A ins(6A, U, 10A) del(6A) ins(6A, U, 10A)del(6A) C O N T I U O U S 1A 2A 3A 4A 5A 6A 10A 7A 8A 9A
- 52. REPLICATED GROWABLE ARRAYS HOW TO REPLICATE OPERATIONS?
- 53. • We need to ensure that every operation was received by every node… • … and at the same time we cannot wait for confirmation before displaying it. IS THERE ANY PROBLEM?
- 54. • We need to ensure that every operation was received by every node… • … and at the same time we cannot wait for confirmation before displaying it. IS THERE ANY PROBLEM?
- 55. EVENTSOURCING Alice (1, ins(1A, ‘H’, 2A)) (2, ins(2A, ‘e’, 3A)) (3, ins(3A, ‘l’, 4A)) (4, ins(4A, ‘l’, 5A)) (5, ins(5A, ‘o’, 6A))
- 56. PARTIALLY ORDERED LOG Alice . . . ins(6A, ‘o’, 7A) ins(7A, ‘u’, 8A) ins(8A, ‘s’, 9A) ins(6A, ‘u’, 10A) ins(6A, ‘n’, 10B) Bob . . . ins(6A, ‘o’, 7A) ins(7A, ‘u’, 8A) ins(8A, ‘s’, 9A) ins(6A, ‘n’, 10B) ins(6A, ‘u’, 10A)
- 57. Other “features”? 1. File format?PARTIALLY ORDERED LOG
- 58. Other “features”? 1. File format?PARTIALLY ORDERED LOG
- 59. Other “features”? 1. File format? 2. History (undo/redo) PARTIALLY ORDERED LOG
- 61. BLOCK-WISE REPLICATED GROWABLE ARRAYS … OR HOW TO ADD MORE THAN ONE CHAR AT THE TIME
- 62. METADATA OVERHEAD H 1 A 2 A ACTUAL PAYLOAD (SINGLE CHARACTER) CURRENT POSITION NEXT CHAR POSITION
- 63. ABSOLUTE POSITION + OFFSET 1A:0ABSOLUTE INDEX ID + REPLICA ID BLOCK OFFSET
- 65. COMPAR ING VECTOR CLOCKS BLOCKWISE REPLICATED GROWABLE ARRAY I WAS EXPECTING IT 1A:0 ins(1A:5, NOT, 2B)
- 66. COMPAR ING VECTOR CLOCKS BLOCKWISE REPLICATED GROWABLE ARRAY I WAS 1A:0 ins(1A:5, NOT, 2B) EXPECTING IT 1A:5 link
- 68. BLOCKWISE REPLICATED GROWABLE ARRAYS DELETING BLOCK OF DATA
- 69. TOMBSTONING I WAS 1A:0 EXPECTING IT 1A:5 link NOT 2B:0 del(1A:12, 3) BLOCKWISE REPLICATED GROWABLE ARRAYS
- 71. I WAS 1A:0 EXPECT 1A:5 link NOT 2B:0 del(1A:12, 3) ITING 1A:12 1A:15 link link BLOCKWISE REPLICATED GROWABLE ARRAYS TOMBSTONING
- 72. I WAS 1A:0 EXPECT 1A:5 link NOT 2B:0 IT--- 1A:12 1A:15 link link BLOCKWISE REPLICATED GROWABLE ARRAYS TOMBSTONING
- 73. TOMBSTONES HOW TO GET RID OF THEM?
- 74. WE CAN ONLY INSERT ELEMENTS AFTER BLOCKS WE SEE (NOT TOMBSTONES)
- 75. I WAS 1A:0 EXPECTING IT 1A:5 link t1 2B:0 del(1A:12, 3, t3) TOMBSTONE PRUNNING
- 76. I WAS 1A:0 EXPECT 1A:5 link t1 2B:0 ITt3 1A:12 1A:15 link link TOMBSTONE PRUNNING
- 77. I WAS 1A:0 EXPECT 1A:5 link t1 2B:0 ITt3 1A:12 1A:15 link link TOMBSTONE PRUNNING prune(t2)
- 78. I WAS 1A:0 EXPECT 1A:5 link t1 2B:0 ITt3 1A:12 1A:15 link link TOMBSTONE PRUNNING t1 < t2
- 79. I WAS 1A:0 EXPECT 1A:5 link ITt3 1A:12 1A:15 link link TOMBSTONE PRUNNING t3 > t2
- 80. I WAS 1A:0 EXPECT 1A:5 link ITt3 1A:12 1A:15 link link TOMBSTONE PRUNNING
- 81. CAN WE USE WALLCLOCK TIME FOR TIMESTAMPING?
- 82. “In transactions, timekeeping is more about order of operations than actual time.”
- 83. SEQUENCERS Set X = 1 ts = 1 Set Y = 2 ts = 2 Set X = 3 ts = 3 Delete Y ts = 4 Set Y = 1 ts = 5 Delete X ts = 6 Monotonically incrementing counter timeline Node A
- 84. DOTS Set X = 1 A:1 Set X = 3 A:2 Set Y = 1 A:3 Delete X A:4 timeline Node A Set Y = 2 B:1 Delete Y B:2 timeline Node B
- 85. VECTOR CLOCKS Set X = 1 Set X = 3 Set Y = 1 Delete X Node A Set Y = 2 Delete Y Node B A 1 A 1 B 1 A 2 B 1 A 2 B 2 A 3 B 2 A 4 B 2
- 86. COMPAR ING VECTOR CLOCKS PARTIAL ORDERING Equals Greater than Less than Concurrent A 2 B 3 C 1 A 2 B 3 C 1 A 2 B 3 C 2 A 2 B 3 C 1 A 2 B 2 C 1 A 2 B 3 C 1 A 2 B 3 C 1 A 2 B 2 C 2 = = = = = > = < = = > <
- 87. COMPAR ING VECTOR CLOCKS RESOLVING CONCURRENT UPDATES Node 1 Node 2 Bob Joe t1 SET X = 2SET X = 1 t2
- 88. COMPAR ING VECTOR CLOCKS RESOLVING CONCURRENT UPDATES Node 1 Node 2 Bob Joe t1 SET X = 2SET X = 1 t2 max (t1, t2) max (t1, t2)
- 90. VECTOR CLOCK MERGE MAX ( , ) = A 1 B 3 A 2 B 1 C 1 A 2 B 3 C 1
- 91. HOW TO DETERMINE “SEEN BY ALL”? DOT VECTOR CLOCK ???
- 92. MATRIX CLOCKS 2 2 1 2 3 1 1 2 2 A B C A B C Observers Observed
- 93. MATRIX CLOCKS 2 2 1 2 3 1 1 2 2 A B C A B C SEEN-BY-ALL MIN
- 94. MATRIX CLOCKS 2 2 1 2 3 1 1 2 2 A B C A B C SEEN-BY-ALL MIN 1 2 1
- 95. MATRIX CLOCKS 2 2 1 2 3 1 1 2 2 A B C A B C SEEN-BY-ALL MIN 1 2 1 Our pruning point
- 96. I WAS 1A:0 EXPECTING IT 1A:5 link {A:2, B:2} 2B:0 del(1A:12, 3, {A:4,B:2}) TOMBSTONE PRUNNING
- 97. I WAS 1A:0 EXPECT 1A:5 link {A:2, B:2} 2B:0 IT{A:4, B:2} 1A:12 1A:15 link link TOMBSTONE PRUNNING
- 98. I WAS 1A:0 EXPECT 1A:5 link {A:2, B:2} 2B:0 IT{A:4, B:2} 1A:12 1A:15 link link TOMBSTONE PRUNNING prune({A:3,B:2})
- 99. I WAS 1A:0 EXPECT 1A:5 link {A:2, B:2} 2B:0 IT{A:4, B:2} 1A:12 1A:15 link link TOMBSTONE PRUNNING {A:2,B:2} < {A:3,B:2}
- 100. I WAS 1A:0 EXPECT 1A:5 link IT{A:4, B:2} 1A:12 1A:15 link link TOMBSTONE PRUNNING {A:4,B:2} > {A:3,B:2}
- 101. I WAS 1A:0 EXPECT 1A:5 link IT{A:4, B:2} 1A:12 1A:15 link link TOMBSTONE PRUNNING
- 102. Operational transformation discussion on HN: https://news.ycombinator.com/item?id=12311984 JSON CRDT by Martin Kleppman: https://www.youtube.com/watch?v=B5NULPSiOGw Rope data structure: https://www.geeksforgeeks.org/ropes-data-structure-fast-string-concatenation/ Blockwise Replicated Growable Arrays: https://pages.lip6.fr/Marc.Shapiro/papers/rgasplit-group2016-11.pdf Examples of CRDT implementations: https://github.com/Horusiath/crdt-examples/ REFERENCES
- 103. THANK YOU