Re: logical decoding : exceeded maxAllocatedDescs for .spill files

On Wed, Nov 20, 2019 at 12:28 AM Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com> wrote:
> On Tue, 19 Nov 2019 at 14:07, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > No, I got this before applying the patch. However, after applying the
> > patch, I got below error in the same test:
> >
> > postgres=# SELECT 1 from
> > pg_logical_slot_get_changes('regression_slot', NULL,NULL) LIMIT 1;
> > ERROR: could not read from reorderbuffer spill file: Invalid argument
> >
> > It seems to me that FileRead API used in the patch can return value <
> > 0 on EOF. See the API usage in BufFileLoadBuffer. I got this error
> > on a windows machine and in the server log the message was "LOG:
> > unrecognized win32 error code: 38" which indicates "Reached the end of
> > the file."
>
> On Windows, it is documented that ReadFile() (which is called by
> pg_pread) will return false on EOF but only when the file is open for
> asynchronous reads/writes. But here we are just dealing with usual
> synchronous reads. So pg_pread() code should indeed return 0 on EOF on
> Windows. Not yet able to figure out how FileRead() managed to return
> this error on Windows. But from your symptoms, it does look like
> pg_pread()=>ReadFile() returned false (despite doing asynchronous
> reads), and so _dosmaperr() gets called, and then it does not find the
> eof error in doserrors[], so the "unrecognized win32 error code"
> message is printed. May have to dig up more on this.

Hmm. See also this report:

https://www.postgresql.org/message-id/flat/CABuU89MfEvJE%3DWif%2BHk7SCqjSOF4rhgwJWW6aR3hjojpGqFbjQ%40mail.gmail.com