Commitfest remaining "Needs Review" items

Hello Hackers,

There are a few "Needs Review" items remaining in the July commitfest. 
Reviewers, please take action - you are holding up the commitfest.

In addition to these items, there are a bunch of items in "Ready for 
Committer" state. Committers: please help with those.

> * extends pgbench expressions with functions

Robert signed up as reviewer for this a long time ago. Ping, do you 
still plan to review this?

> * self-defined policy for sepgsql regression test

Stephen: would you have the time to handle this, please?

> * Allocate restart_lsn at the time of creating physical replication slot

Andres, can you have a look at this, please?

> * Parallel Seq scan

Jeff, Haribabu, you're signed up as reviewers. How's it going?

> * Join pushdown support for foreign tables

Ashutosh, KaiGai, Etsuro: You signed up as reviewers in spring, but 
there hasn't been any activity during this commitfest. What's the status 
of this patch? Do you plan to review this now?

> * replace pg_stat_activity.waiting with something more descriptive

This is not quite ready yet, but has had its fair share of review, so 
I'm going to move it to the next commitfest. Feel free to continue the 
discussion and review, though; I just don't want drag the commitfest 
because for this.

> * Unique Joins

Still needs to be reviewed. Any volunteers?

> * checkpoint continuous flushing

Per discussion on that thread, let's just do the sorting part now. Needs 
some cleanup, but it's almost there.

- Heikki