如何使用 CTE 从 Postgres 函数返回值

Question

我正在努力让以下函数在成功插入记录时返回一个值，并且在它不插入任何数据时不返回任何行。

我已经测试了这个函数，两个插入语句运行良好。 正在插入正确的数据。 我只是无法获得返回最后插入的 ID（rarefaction_id）的函数。 我尝试使用带有 return 语句的 plpgsql，但遇到了同样的问题。

create or replace function sample.fn_next_rarefaction()
    returns table
            (
                rarefaction_id int
            )
    language sql
as
$$
with translations_required as
        (
            select s.sample_id,
                    m.translation_id,
                    m.fixed_count
            from sample.box_models bm
                    inner join sample.samples s on bm.box_id = s.box_id
                    inner join geo.models m on bm.model_id = m.model_id
            where translation_id is not null
            union
            select ps.sample_id,
                    m.translation_id,
                    m.fixed_count
            from sample.project_samples ps
                    inner join sample.project_models pm on ps.project_id = pm.project_id
                    inner join geo.models m on pm.model_id = m.model_id
            where translation_id is not null
            union
            select sample_id, 2, 300
            from sample.samples
        ),
    next_rarefaction as
        (
            select tr.*
            from translations_required tr
                    left join sample.rarefactions r on tr.sample_id = r.sample_id
                and coalesce(tr.translation_id, -1) = coalesce(r.translation_id, -1)
                and coalesce(tr.fixed_count, -1) = coalesce(r.fixed_count, -1)
            where r.sample_id is null
            limit 1
        ),
    insert_rarefactions as
        (
            -- upsert the rarefactions record. Should only return rows when new record inserted.
            insert into sample.rarefactions (sample_id, translation_id, fixed_count)
                select sample_id,
                        translation_id,
                        fixed_count
                from next_rarefaction
                on conflict do nothing
                returning rarefaction_id, sample_id, translation_id, fixed_count
        ),
    insert_rarefaction as
        (
            insert
                into sample.rarefied_organisms (rarefaction_id, taxonomy_id, split_count)
                    select ir.rarefaction_id,
                            sr.taxonomy_id,
                            sr.split_count
                    from insert_rarefactions ir
                            inner join lateral sample.rarefy(ir.sample_id, ir.translation_id, ir.fixed_count) sr
                                        on true
                    returning rarefaction_id
        )
    select rarefaction_id from insert_rarefaction;
$$;