Horton

Re: automatically generating node support functions

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Cc: David Rowley <dgrowleyml@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-07-03T19:14:09Z
Lists: pgsql-hackers 
Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:
> Here is a patch that reformats the relevant (and a few more) comments 
> that way.  This has been run through pgindent, so the formatting should 
> be stable.

Now that that's been pushed, the main patch is of course quite broken.
Are you working on a rebase?

I looked through the last published version of the main patch (Alvaro's
0002 from 2022-04-19), without trying to actually test it, and found
a couple of things that look wrong in the Makefiles:

* AFAICT, the infrastructure for removing the generated files at
"make *clean" is incomplete.  In particular I don't see any code
for removing the symlinks or the associated stamp file during
"make clean".  It looks like the existing header symlinks are
all cleaned up in src/include/Makefile's "clean" rule, so you
could do likewise for these.  Also, the "make maintainer-clean"
infrastructure seems incomplete --- shouldn't src/backend/Makefile's
maintainer-clean rule now also do
	$(MAKE) -C nodes $@
?

* There are some useful comments in backend/utils/Makefile that
I think should be carried over along with the make rules that
(it looks like) you cribbed from there, notably

# fmgr-stamp records the last time we ran Gen_fmgrtab.pl.  We don't rely on
# the timestamps of the individual output files, because the Perl script
# won't update them if they didn't change (to avoid unnecessary recompiles).

# These generated headers must be symlinked into builddir/src/include/,
# using absolute links for the reasons explained in src/backend/Makefile.
# We use header-stamp to record that we've done this because the symlinks
# themselves may appear older than fmgr-stamp.

and something similar to this for the "clean" rule:
# fmgroids.h, fmgrprotos.h, fmgrtab.c, fmgr-stamp, and errcodes.h are in the
# distribution tarball, so they are not cleaned here.


Also, I share David's upthread allergy to the option names "path_hackN"
and to documenting those only inside the conversion script.  I think
the existing text that you moved into the script, such as this bit:

		# We do not print the parent, else we'd be in infinite
		# recursion.  We can print the parent's relids for
		# identification purposes, though.  We print the pathtarget
		# only if it's not the default one for the rel.  We also do
		# not print the whole of param_info, since it's printed via
		# RelOptInfo; it's sufficient and less cluttering to print
		# just the required outer relids.

is perfectly adequate as documentation, it just needs to be somewhere else
(pathnodes.h seems fine, if not nodes.h) and labeled as to exactly which
pg_node_attr option invokes which behavior.

BTW, I think this: "Unknown attributes are ignored" is a seriously
bad idea; it will allow typos to escape detection.

			regards, tom lane

Commits

  1. Fix MSVC build script's check for obsolete node support functions.

  2. Improve performance of ORDER BY / DISTINCT aggregates

  3. doc: Fix typos in protocol.sgml

  4. Tighten up parsing logic in gen_node_support.pl.

  5. Add defenses against unexpected changes in the NodeTag enum list.

  6. Add copy/equal support for XID lists

  7. Rationalize order of input files for gen_node_support.pl.

  8. Make assorted quality-of-life improvements in gen_node_support.pl.

  9. Doc: rearrange high-level commentary about node support coverage.

  10. Automatically generate node support functions

  11. Adjust node serialization tag of A_Expr for consistency

  12. Remove T_Join and T_Plan

  13. Reformat some more node comments

  14. Reformat some node comments

  15. Remove JsonPathSpec typedef

  16. Add missing enum tag in enum used in nodes

  17. Add Cardinality typedef

  18. Make node output prefix match node structure name

  19. Add WRITE_INDEX_ARRAY

  20. Add COPY_ARRAY_FIELD and COMPARE_ARRAY_FIELD

  21. Remove T_Expr

  22. Change NestPath node to contain JoinPath node

  23. Change SeqScan node to contain Scan node

  24. Check the size in COPY_POINTER_FIELD

  25. Remove T_MemoryContext

  26. Add missing enum tags in enums used in nodes

  27. Rename some node support functions for consistency

  28. Rename argument of _outValue()

  29. Rename NodeTag of ExprState