JSON indexes for posts

posts-by-lang.sql

@@ -0,0 +1,28 @@
+create index post_langs on records_post using gin (jsonb_extract_path(content, 'langs') jsonb_ops);
+
+-- There are invalid/non-conforming values that need to be handled somehow.
+create function parse_timestamp(text)
+  returns timestamp
+  returns null on null input
+  immutable
+  as
+  $$
+  begin
+    begin
+      return $1::timestamp;
+    exception
+      when others then
+        return null;
+    end;
+  end;
+  $$
+  language plpgsql;
+
+create index post_created_at on records_post (parse_timestamp(jsonb_extract_path_text(content, 'createdAt')));
+
+create view posts as
+  select *, jsonb_extract_path(content, 'langs') as langs,
+    parse_timestamp(jsonb_extract_path_text(content, 'createdAt')) as created_at
+    from records_post;
+
+explain select count(*) from posts where langs ? 'uk' and content_created_at > now() - interval '1 day';