Add postgresql-unit extension

nix/ext/postgresql-unit.nix

@@ -0,0 +1,38 @@
+{ lib, stdenv, fetchFromGitHub, postgresql, flex, bison }:
+
+stdenv.mkDerivation rec {
+  pname = "postgresql-unit";
+  version = "7.10";
+  name = "postgresql-unit";
+  buildInputs = [ postgresql ];
+  nativeBuildInputs = [ flex bison ];
+
+  src = fetchFromGitHub {
+    owner = "df7cb";
+    repo = pname;
+    rev = "${version}";
+    hash = "sha256-glVyW0n34I3QArlTscV+p1/sfhIfFbeH192rf9uYJp0=";
+  };
+
+
+  installPhase = ''
+    mkdir -p $out/{lib,share/postgresql/extension}
+
+    # Fix the @MODULEDIR@ / postgresql path reference
+    substituteInPlace *.sql \
+      --replace "${postgresql}/share/postgresql/extension/" "$out/share/postgresql/extension/"
+
+    cp *.so $out/lib
+    cp *.sql $out/share/postgresql/extension
+    cp *.data $out/share/postgresql/extension
+    cp *.control $out/share/postgresql/extension
+
+  '';
+
+  meta = with lib; {
+    description = "postgresql-unit implements a PostgreSQL datatype for SI units, plus byte.";
+    homepage = "https://github.com/${src.owner}/${src.repo}";
+    platforms = postgresql.meta.platforms;
+    license = licenses.gpl3;
+  };
+}

nix/packages/postgres.nix

@@ -50,6 +50,7 @@
         ../ext/wrappers/default.nix
         ../ext/supautils.nix
         ../ext/plv8
+        ../ext/postgresql-unit.nix
       ];
 
       #Where we import and build the orioledb extension, we add on our custom extensions