Hi,
Since [1] walsender (not receiver as commit message says) can execute
SQL queries. While doing some testing of [2] I noticed that SQL queries
in walsender get stuck if parallelism is used - I have not investigated
why that is yet, but it surely is an issue. On first blush I'd suspect
that some signalling is not wired up correctly (cf. am_walsender branches
in PostgresMain() and such).
This'd be easier to look at if the fairly separate facility of allowing
walsender to execute SQL commands had been committed separately, rather
than as part of a fairly large commit of largely unrelated things.
Greetings,
Andres Freund
[1] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=7c4f52409a8c7d85ed169bbbc1f6092274d03920
[2] http://archives.postgresql.org/message-id/30242bc6-eca4-b7bb-670e-8d0458753a8c%402ndquadrant.com
