| Started thread | ALTER TYPE 6: numeric | about 15 years ago | Patch |
| Started thread | ALTER TYPE 5: varbit and bit | about 15 years ago | Patch |
| Started thread | ALTER TYPE 4: temporal data types | about 15 years ago | Patch |
| Started thread | ALTER TYPE 3: add facility to identify further no-work cases | about 15 years ago | Patch |
| Started thread | ALTER TYPE 2: skip already-provable no-work rewrites | about 15 years ago | Patch |
| Started thread | ALTER TYPE 1: recheck index-based constraints | about 15 years ago | Patch |
| Started thread | ALTER TYPE 0: Introduction; test cases | about 15 years ago | Patch |