> On Thu, Jun 13, 2019 at 1:38 PM Pavel Trukhanov <pavel.trukha...@gmail.com> > wrote: > > Hi Hackers > > I would like to embark on a journey to try to implement this issue I > found on TODO list – > https://www.postgresql.org/message-id/flat/CAM3SWZSpdPB3uErnXWMt3q74y0r%2B84ZsOt2U3HKKes_V7O%2B0Qg%40mail.gmail.com > In short: pgss distinguishes "SELECT * WHERE id IN (1, 2)" and "SELECT > * WHERE id IN (1, 2, 3)" as two separate queryId's, resulting in > separate entries in pgss. While in practice in most cases it should be > considered as the same thing. > > Though it was added in TODO by Bruce Momjian some time ago, I > personally have been annoyed by this issue, because we use pgss as a > data source in our monitoring system okmeter.io – so we've been using > some work arounds for this in our system.
Thanks! One more time stumbled upon it just now, so I agree it would be nice. > 1. ArrayExpr > ArrayExpr is used to represent not only "IN" clauses, but also for > example "SELECT ARRAY[1, 2, 3]" and maybe some other cases I didn't > think of. > That brings the question whether "IN (...)" should be handled > separately from actual usage of ARRAY. If I understand correctly, "IN (...)" is reprecented by A_Expr with kind AEXPR_IN, and only in transformAExprIn converted to ArrayExpr if possible. So probably it doesn't makes sense to introduce another one. > For example "SELECT ARRAY[1, 2, a] FROM table" and "SELECT ARRAY[b] > FROM table" might end up in the same pgss entry. What are a, b here, parameters? > 3 Tests in pgss.sql/out and Vars > I would like someone to point me in a direction of how could I > implement a test that will query > "SELECT * FROM test WHERE a IN ($1, $2, $3, ...)" with params, not > consts Wouldn't a prepared statement work? It will create an ArrayExpr with Params inside.
