Re: Lets (not) break all the things. Was: [pgsql-advocacy] 9.6 -> 10.0

Here's the features I can imagine being worth major backwards
compatibility breaks:

1. Fully pluggable storage with a clean API.

2. Total elimination of VACUUM or XID freezing

3. Fully transparent-to-the user MM replication/clustering or sharding.

4. Perfect partitioning (i.e. transparent to the user, supports keys &
joins, supports expressions on partition key, etc.)

5. Transparent upgrade-in-place (i.e. allowing 10.2 to use 10.1's tables
without pg_upgrade or other modification).

6. Fully pluggable parser/executor with a good API

That's pretty much it.  I can't imagine anything else which would
justify imposing a huge upgrade barrier on users.  And, I'll point out,
that in the above list:

* nobody is currently working on anything in core except #4.

* we don't *know* that any of the above items will require a backwards
compatibility break.

People keep talking about "we might want to break compatibility/file
format one day".  But nobody is working on anything which will and
justifies it.