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: Andres Freund <andres@anarazel.de>
Cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>, David Rowley <dgrowleyml@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-07-11T21:18:57Z
Lists: pgsql-hackers

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I wrote:
> Andres Freund <andres@anarazel.de> writes:
>> Additionally, I think we've had to add tags to the enum in minor releases
>> before and I'm afraid this now would end up looking even more awkward?

> Peter and I already had a discussion about that upthread --- we figured
> that if there's a way to manually assign a nodetag's number, you could use
> that option when you have to add a tag in a stable branch.  We didn't
> actually build out that idea, but I can go do that, if we can solve the
> more fundamental problem of keeping the autogenerated numbers stable.

> One issue with that idea, of course, is that you have to remember to do
> it like that when back-patching a node addition.  Ideally there'd be
> something that'd carp if the last autogenerated tag moves in a stable
> branch, but I'm not very sure where to put that.

One way to do it is to provide logic in gen_node_support.pl to check
that, and activate that logic only in back branches.  If we make that
part of the branch-making procedure, we'd not forget to do it.

Proposed patch attached.

			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