The pg_walinspect function pg_get_wal_stats() has output arguments
declared as float4 (count_percentage, record_size_percentage, etc.), but
the internal computations are all done in type double. Is there a
reason why this is then converted to float4 for output? It probably
doesn't matter in practice, but it seems unnecessarily confusing. Or at
least add a comment so it doesn't look like an accident. Also compare
with pgstattuple, which uses float8 in its SQL interface for similar data.
