Model
What a structural change touches
It explains why schema evolution is easy in year one and enormous by year five.
How it behaves
One input on the horizontal axis, the others held fixed.
Data table
| Months of data | Reader-months of exposure |
|---|---|
| 1 | 3.15 |
| 1.74 | 5.67 |
| 2.48 | 8.34 |
| 3.21 | 11.2 |
| 3.95 | 14.2 |
| 4.69 | 17.4 |
| 5.42 | 20.7 |
| 6.16 | 24.2 |
| 6.9 | 27.8 |
| 7.64 | 31.7 |
| 8.38 | 35.6 |
| 9.11 | 39.8 |
| 9.85 | 44.1 |
| 10.6 | 48.6 |
| 11.3 | 53.2 |
| 12.1 | 58 |
| 12.8 | 63 |
| 13.5 | 68.1 |
| 14.3 | 73.4 |
| 15 | 78.8 |
| 15.8 | 84.5 |
| 16.5 | 90.2 |
| 17.2 | 96.2 |
| 18 | 102 |
| 18.7 | 109 |
| 19.4 | 115 |
| 20.2 | 122 |
| 20.9 | 128 |
| 21.6 | 135 |
| 22.4 | 142 |
| 23.1 | 150 |
| 23.9 | 157 |
| 24.6 | 165 |
| 25.3 | 172 |
| 26.1 | 180 |
| 26.8 | 188 |
| 27.6 | 197 |
| 28.3 | 205 |
| 29 | 213 |
| 29.8 | 222 |
| 30.5 | 231 |
| 31.2 | 240 |
| 32 | 249 |
| 32.7 | 259 |
| 33.5 | 268 |
| 34.2 | 278 |
| 34.9 | 288 |
| 35.7 | 298 |
| 36.4 | 308 |
| 37.1 | 318 |
| 37.9 | 329 |
| 38.6 | 339 |
| 39.4 | 350 |
| 40.1 | 361 |
| 40.8 | 372 |
| 41.6 | 384 |
| 42.3 | 395 |
| 43 | 407 |
| 43.8 | 419 |
| 44.5 | 431 |
| 45.3 | 443 |
| 46 | 455 |
| 46.7 | 468 |
| 47.5 | 480 |
| 48.2 | 493 |
| 48.9 | 506 |
| 49.7 | 519 |
| 50.4 | 532 |
| 51.1 | 546 |
| 51.9 | 560 |
| 52.6 | 573 |
| 53.4 | 587 |
| 54.1 | 601 |
| 54.8 | 616 |
| 55.6 | 630 |
| 56.3 | 645 |
| 57 | 659 |
| 57.8 | 674 |
| 58.5 | 689 |
| 59.3 | 705 |
| 60 | 720 |
Worked examples, recomputed
Every number the mechanisms quote for this relationship is recomputed from it, so none of them disagrees with it.
Where it appears
Each mechanism states it in its own names. The general symbol each name stands for is shown with it.
- Schema Management & Evolution
What happens when the shape of your data changes on its own schedule, and nobody can change the readers, the writers and the old data at the same moment?