Re: bug or lacking doc hint

2023-06-25 Thread Avin Kavish
Sounds like the problem you are having is, the server is running out of temporary resources for the operation that users are trying to do. So according to Tom, on the postgres side, the operation cannot be optimized further. I think you have few choices here, - See if increasing the resources

Re: bug or lacking doc hint

2023-06-25 Thread Marc Millas
On Sun, Jun 25, 2023 at 11:48 PM Tom Lane wrote: > David Rowley writes: > > The problem is that out of the 3 methods PostgreSQL uses to join > > tables, only 1 of them supports join conditions with an OR clause. > > Merge Join cannot do this because results can only be ordered one way > > at a

Re: bug or lacking doc hint

2023-06-25 Thread Tom Lane
David Rowley writes: > The problem is that out of the 3 methods PostgreSQL uses to join > tables, only 1 of them supports join conditions with an OR clause. > Merge Join cannot do this because results can only be ordered one way > at a time. Hash Join technically could do this, but it would

Re: Helping planner to chose sequential scan when it improves performance

2023-06-25 Thread David Rowley
On Wed, 14 Jun 2023 at 07:28, Patrick O'Toole wrote: > Maybe we are barking up the wrong tree with the previous questions. Are there > other configuration parameters we should consider first to improve > performance in situations like the one illustrated? random_page_cost and

Re: bug or lacking doc hint

2023-06-25 Thread Marc Millas
On Sun, Jun 25, 2023 at 9:35 PM David Rowley wrote: > On Mon, 26 Jun 2023 at 03:02, Marc Millas wrote: > > When I ask this list, David Rowley suggest to rewrite the SQL, replacing > the OR by a union. > > > > Fine, this do work, even if a bit complex as the original SQL was a set > of intricate

Re: bug or lacking doc hint

2023-06-25 Thread David Rowley
On Mon, 26 Jun 2023 at 03:02, Marc Millas wrote: > When I ask this list, David Rowley suggest to rewrite the SQL, replacing the > OR by a union. > > Fine, this do work, even if a bit complex as the original SQL was a set of > intricate joins. > > > So, either this behaviour ( postgres unable to

Re: Helping planner to chose sequential scan when it improves performance

2023-06-25 Thread Jeff Janes
On Tue, Jun 13, 2023 at 3:28 PM Patrick O'Toole wrote: > run the query twice first, then... Is that a realistic way to run the test? Often forcing all the data needed for the query into memory is going to make things less realistic, not more realistic. Assuming the system has more stuff to

Re: bug or lacking doc hint

2023-06-25 Thread Ron
On 6/25/23 10:01, Marc Millas wrote: Hi, I have had a perf (++) pb with a join plan  cf the pb with join plan thread. I did simplify the thing up to when its a simple join between a 15M lines table and a 30k lines table. if I put in the on part something like table1.a=table2.b, Postgres does

Re: Why can't lseek the STDIN_FILENO?

2023-06-25 Thread wen-yi
OK, I see, I'm so sorry for my action. I will ask in cpplang slack community in the future. And really thanks for your advice. Your, Wen Yi --Original-- From:

bug or lacking doc hint

2023-06-25 Thread Marc Millas
Hi, I have had a perf (++) pb with a join plan cf the pb with join plan thread. I did simplify the thing up to when its a simple join between a 15M lines table and a 30k lines table. if I put in the on part something like table1.a=table2.b, Postgres does the job in around 1 seconde. if in the