On Fri, Jul 19, 2024 at 7:20 AM Paul George <p.a.georg...@gmail.com> wrote:
> > I wanted to surface a discussion in [1] regarding the expected behavior of > GROUP BY with VOLATILE expressions. There seems to be a discrepancy between > how volatile functions (RANDOM(), also confirmed with TIMEOFDAY()) and > subqueries are evaluated in groups. In the examples below, volatile > functions do not always appear to be evaluated per-call (evidenced by > looking at EXPLAIN or results) whereas scalar subqueries always appear to > be independently evaluated. > > Based on the docs, "A query using a volatile function will re-evaluate > the function at every row where its value is needed," it seems that the > handling of subqueries is correct and that each call to RANDOM() should be > evaluated (not the current behavior). But, what is correct/anticipated? > > The observed behaviors are unlikely to change. Prior discussions can be found regarding this: https://www.postgresql.org/message-id/flat/CZHAF947QQQO.27MAUK2SVMBXW%40nmfay.com David J.
