Re: making the backend's json parser work in frontend code

On Thu, Jan 23, 2020 at 1:05 PM Mark Dilger
<mark(dot)dilger(at)enterprisedb(dot)com> wrote:
> Ok, I finished merging with Robert’s patches. The attached follow his numbering, with my patches intended to by applied after his.

I think it'd be a good idea to move the pg_wchar.h stuff into a new
thread. This thread is getting a bit complicated, because we've got
(1) the patches need to do $SUBJECT plus (2) additional patches that
clean up the multibyte stuff more plus (3) discussion of issues that
pertain to the backup manifest thread. To my knowledge, $SUBJECT
doesn't strictly require the pg_wchar.h changes, so I suggest we try
to segregate those.

> I tried not to change his work too much, but I did a bit of refactoring in 0010, as explained in the commit comment.

Hmm, I generally prefer to avoid these kinds of macro tricks because I
think they can be confusing to the reader. It's worth it in a case
like equalfuncs.c where so much boilerplate code is saved that the
gain in readability more than makes up for having to go check what the
macros do -- but I don't feel that's the case here. There aren't
*that* many call sites, and I think the code will be easier to
understand without "return" statements concealed within macros...

> I ran some benchmarks for json parsing in the backend both before and after these patches, with very slight changes in runtime.

Cool, thanks.

Since 0001-0003 have been reviewed by multiple people and nobody's
objected, I have committed those. But I made a hash of it: the first
one, I failed to credit any reviewers, or include a Discussion link,
and I just realized that I should have listed Alvaro's name as a
reviewer also. Sorry about that.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company