On 18th of July, Robert Haas committed patch: Avoid index rebuild for no-rewrite ALTER TABLE .. ALTER TYPE. Noah Misch. Review and minor cosmetic changes by me.

On 12th of February, Robert Haas committed patch: Teach ALTER TABLE .. SET DATA TYPE to avoid some table rewrites.   When the old type is binary coercible to the new type and the using clause does not change ...

On 28th of July, Simon Riggs committed patch which: Log Message: ----------- Reduce lock levels of CREATE TRIGGER and some ALTER TABLE, CREATE RULE actions. Avoid hard-coding lockmode used for many altering DDL commands, allowing easier future changes of lock levels. Implementation of initial analysis ...