Re: WIP: WAL prefetch (another approach)

Hm. I seem to have picked a bad checkout. I took the last one before
the revert (45aa88fe1d4028ea50ba7d26d390223b6ef78acc). Or there's some
incompatibility with the emulation and the IPC stuff parallel workers
use.


2021-12-17 17:51:51.688 EST [50955] LOG:  background worker "parallel
worker" (PID 54073) was terminated by signal 10: Bus error
2021-12-17 17:51:51.688 EST [50955] DETAIL:  Failed process was
running: SELECT variance(unique1::int4), sum(unique1::int8),
regr_count(unique1::float8, unique1::float8)
FROM (SELECT * FROM tenk1
      UNION ALL SELECT * FROM tenk1
      UNION ALL SELECT * FROM tenk1
      UNION ALL SELECT * FROM tenk1) u;
2021-12-17 17:51:51.690 EST [50955] LOG:  terminating any other active
server processes
2021-12-17 17:51:51.748 EST [54078] FATAL:  the database system is in
recovery mode
2021-12-17 17:51:51.761 EST [50955] LOG:  all server processes
terminated; reinitializing