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: Robert Haas <robertmhaas@gmail.com>
Cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Andres Freund <andres@anarazel.de>, David Rowley <dgrowleyml@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-07-11T19:54:22Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Jul 11, 2022 at 1:57 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> More generally, I'm having second thoughts about the wisdom of
>> auto-generating the NodeTag enum at all.  With the current setup,
>> I am absolutely petrified about the risk of silent ABI breakage
>> thanks to the enum order changing.

> I think this is a valid concern, but having it be automatically
> generated is awfully handy, so I think it would be nice to find some
> way of preserving that.

Agreed.  The fundamental problem seems to be that each build toolchain
has its own source of truth about the file processing order, but we now
see that there had better be only one.  We could make the sole source
of truth about that be gen_node_support.pl itself, I think.

We can't simply move the file list into gen_node_support.pl, because
(a) the build system has to know about the dependencies involved, and
(b) gen_node_support.pl wouldn't know what to do in VPATH situations.
However, we could have gen_node_support.pl contain a canonical list
of the files it expects to be handed, and make it bitch if its
arguments don't match that.

That's ugly I admit, but the set of files of interest doesn't change
so often that maintaining one additional copy would be a big problem.

Anybody got a better idea?

			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