Hi Andrei, On Fri, Oct 11, 2024 at 8:21 AM Andrei Lepikhov <lepi...@gmail.com> wrote:
> On 10/10/24 23:51, Robert Haas wrote: > > On Wed, Sep 18, 2024 at 11:48 AM Robert Haas <robertmh...@gmail.com> > wrote: > > 1. If you want to specify in-query hints using comments, how does your > > extension get access to the comments? > Having designed two features [1,2] that do the stuff mostly similar to > pg_hint_plan but based on real cardinalities earned from previous > executions, I can say the most annoying problem is hinting subqueries & > CTEs. Sometimes, you want to hint at the top query and not touch the > subquery and vice versa. Sometimes, users get stuck in accidents when a > flattened subquery influences your hint. So, the key property to invent > in advance should be an identification system. > I have chosen hash-based identification when each RelOptInfo has a hash > created over values of relids, restrictions and hashes of underlying > RelOptInfos. At the core, it seems inappropriate. > out of curiosity, why do You think it would be inappropriate to do so in the core? Maybe it Is something similiar to compute_query_id that can be computed externally too. I remember Tom arguing that query_id should be computed externally by extension for some reasons because each extension may want differently to fingerprint the queries, but I cannot find link to discussion now or bring more details) -J.
