Building datasketches-postgresql with nix

[Marko Mušnjak]

Hi,

I was playing around learning Nix and chose a little project for myself:
build a postgres package with some extensions,
including datasketches-postgresql. Since that took a lot of tinkering, I
thought I'd share this here in case anyone ever needs it.

The cause of the struggle seems to be in some build
steps datasketches-postgresql needs, but Nix doesn't make very obvious.

The working nix package is below:

{
  pkgs ? import <nixpkgs> {}
}:
let
  postgres = pkgs.postgresql_15;
  boost = pkgs.boost182;

  cpp_version = "4.1.0";
  cpp_sources = pkgs.fetchFromGitHub {
    owner  = "apache";
    repo   = "datasketches-cpp";
    rev    = "refs/tags/${cpp_version}";
    sha256 = "sha256-vPoFzRxOXlEAiiHH9M5S6255ahzaKsGNYS0cdHwrRYw=";
  };
in
pkgs.stdenv.mkDerivation rec {
  pname = "pg-datasketches";
  version = "1.6.0";

  src = pkgs.fetchFromGitHub {
    owner  = "apache";
    repo   = "datasketches-postgresql";
    rev    = "refs/tags/${version}";
    sha256 = "sha256-sz94fIe7nyWhjiw8FAm6ZzVpB0sAK5YxUrtbaZt/guA=";
  };

  nativeBuildInputs = [ postgres boost cpp_sources ];

  patchPhase = ''
    cp -r ${cpp_sources} datasketches-cpp
  '';

  installPhase = ''
    install -D -m 644 ./datasketches.so -t $out/lib/
    cat \
      sql/datasketches_cpc_sketch.sql \
      sql/datasketches_kll_float_sketch.sql \
      sql/datasketches_kll_double_sketch.sql \
      sql/datasketches_theta_sketch.sql \
      sql/datasketches_frequent_strings_sketch.sql \
      sql/datasketches_hll_sketch.sql \
      sql/datasketches_aod_sketch.sql \
      sql/datasketches_req_float_sketch.sql \
      sql/datasketches_quantiles_double_sketch.sql \
      > sql/datasketches--${version}.sql
    install -D -m 644 ./datasketches.control -t
$out/share/postgresql/extension
    install -D -m 644 \
      ./sql/datasketches--${version}.sql \
      ./sql/datasketches--1.3.0--1.4.0.sql \
      ./sql/datasketches--1.4.0--1.5.0.sql \
      ./sql/datasketches--1.5.0--1.6.0.sql \
      -t $out/share/postgresql/extension
  '';
}

Cheers,
Marko