Re: pg_*_advice: tsv load failure, etc.

On Thu, Sep 10, 2026 at 9:42 AM Melanie Plageman
<melanieplageman(at)gmail(dot)com> wrote:
> What is your plan with cross- release compatibility for the mini
> language and what advice strings are valid across releases?

I think cross-release compatibility should be pretty good, but it
won't be perfect. Some planner changes are going to require, or at
least invite, corresponding changes to the advice language. If for
example we remove sequential scans, then supporting SEQ_SCAN(blah)
won't make sense any more. I recommend against removing sequential
scans, but you get the point. Conversely, since Richard has added
eager aggregation, it would be nice to add EAGER_AGG(...), but I left
all aggregation out of scope for v19 due to lack of time. Basically,
this feature is going to require maintenance like any other, and will
have compatibility breaks just like SQL itself, but hopefully not a
lot of maintenance and not a lot of compatibility breaks.

> On some
> level, idea 1 seems like the most appealing because a) it seems quick
> to do before beta 4 b) it's the easiest to back down from if you find
> a good way to support this later. If you don't require the schema and
> later have to do that, you could have advice strings that no longer
> work.

Fair point. Let me poke at this some more.

> Take this with a grain of salt, as I have neither used the
> feature nor looked at its code :)

I fear you're far from alone in that.

--
Robert Haas
EDB: http://www.enterprisedb.com