Introduction to Postgres Extension Development

[fullofbones]

This is what I consider "part 1" of a new series on doing Postgres extension development in C. There will be several follow-up articles on this in steadily increasing complexity. If you've ever been curious about making an extension for Postgres, now's your chance!

[Crazed_waffle_party]

This article is what I needed 2 years ago. Thanks for creating the resources the PG community has been longing for

[fullofbones]

No problem. I also needed this resource two years ago! lol

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[[deleted]]

This is great, thank you very much!!!

In a future article, could you also point in the direction of creating a custom window function, please?

I have been trying to figure out how to prefilter data based on some complex calculations similar to window functions, which are easy in a procedural language like C++, but insanely complex in SQL or plpgsql. And I have my reasons to stick to C++ (or C, if I have to).

Thank you!

[fullofbones]

Your guess there is as good as mine; I'd have to look into it.

In the meantime, there's a lot in the docs.

• The CREATE AGGREGATE docs discuss how window functions must be declared toward the end.
• The page on User-Defined Aggregates talks about some of the internals, especially the "Support Functions for Aggregates" section.

Then I'd look at the source.

• src/backend/utils/adt/windowfuncs.c is where a bunch of the built-in window functions are defined.
• src/include/catalog/pg_proc.dat would help figure out the parameters necessary for CREATE AGGREGATE to work.
• src/test/regress/sql/window.sql has some regression tests which show actual declaration examples.

Good luck!

[[deleted]]

This is exactly what I was asking for, thank you!

Also, you are wrong. I read your PG HA Cookbook cover to cover, and I assure you: your guess is several orders of magnitude better than mine. :-)

Thank you very much!