On Tue, May 1, 2018 at 9:26 AM, Andres Freund <andres@anarazel.de> wrote:
Hi, On 2018-05-01 16:41:04 +0900, Dang Minh Huong wrote: > The syntax is known as, > > pg_waldump [OPTION]... [STARTSEG [ENDSEG]] > > Mean that, it could work with no arguments. > But the "no arguments specified" ERROR will be returned in that case. > > $ pg_waldump > pg_waldump: no arguments specified > Try "pg_waldump --help" for more information. > > I wonder it should be, > > pg_waldump { OPTION... [STARTSEG [ENDSEG]] } | { [OPTION]... STARTSEG [ENDSEG] } > > Have any comments?
To me that doesn't seem like an improvement, looks a good chunk more complicated. You'll get the error and the docs also tell you that some arguments are needed.
Reading the v10 docs...
note: there is either an extra space between the two closing brackets or a missing space before startseg
I suppose it would help to understand why an argument is required - providing a startseg implicitly sets path and timeline but both of those have defaults and so even without a startseg those two aren't required. Since no other options are required when startseg is specified it doesn't make sense that there would be others required when it is not.
IOW, the error message in the no-arg command invocation seems incorrect.