Re: WIP: new system catalog pg_wait_event

On Tue, Aug 08, 2023 at 10:16:37AM +0200, Drouvot, Bertrand wrote:
> Please find attached v3 adding the wait event types.

+-- There will surely be at least 9 wait event types, 240 wait events and at
+-- least 27 related to WAL
+select count(distinct(wait_event_type)) > 8 as ok_type,
+ count(*) > 239 as ok,
+ count(*) FILTER (WHERE description like '%WAL%') > 26 AS ok_wal_desc
+from pg_wait_event;
The point is to check the execution of this function, so this could be
simpler, like that or a GROUP BY clause with the event type:
SELECT count(*) > 0 FROM pg_wait_event;
SELECT wait_event_type, count(*) > 0 AS has_data FROM pg_wait_event
GROUP BY wait_event_type ORDER BY wait_event_type;

+ printf $ic "\tmemset(values, 0, sizeof(values));\n";
+ printf $ic "\tmemset(nulls, 0, sizeof(nulls));\n\n";
+ printf $ic "\tvalues[0] = CStringGetTextDatum(\"%s\");\n", $last;
+ printf $ic "\tvalues[1] = CStringGetTextDatum(\"%s\");\n", $wev->[1];
+ printf $ic "\tvalues[2] = CStringGetTextDatum(\"%s\");\n\n", $new_desc;

That's overcomplicated for some code generated. Wouldn't it be
simpler to generate a list of elements, with the code inserting the
tuples materialized looping over it?

+ my $new_desc = substr $wev->[2], 1, -2;
+ $new_desc =~ s/'/\\'/g;
+ $new_desc =~ s/<.*>(.*?)<.*>/$1/g;
+ $new_desc =~ s/<xref linkend="guc-(.*?)"\/>/$1/g;
+ $new_desc =~ s/; see.*$//;
Better to document what this does, the contents produced look good.

+ rename($ictmp, "$output_path/pg_wait_event_insert.c")
+ || die "rename: $ictmp to $output_path/pg_wait_event_insert.c: $!";

# seems nicer to not add that as an include path for the whole backend.
waitevent_sources = files(
'wait_event.c',
+ 'pg_wait_event.c',
)

This could use a name referring to SQL functions, say
wait_event_funcs.c, with a wait_event_data.c or a
wait_event_funcs_data.c?

+ # Don't generate .c (except pg_wait_event_insert.c) and .h files for
+ # Extension, LWLock and Lock, these are handled independently.
+ my $is_exception = $waitclass eq 'WaitEventExtension' ||
+ $waitclass eq 'WaitEventLWLock' ||
+ $waitclass eq 'WaitEventLock';
Perhaps it would be cleaner to use a separate loop?
--
Michael