Thread: Re: [HACKERS] psql \h alter scrolls of screen

Tom Lane wrote:
> Robert Treat <xzilla@users.sourceforge.net> writes:
> > On Thu, 2003-09-04 at 21:14, Bruce Momjian wrote:
> >> Should we be using the pager for \h output?
>
> > in 7.3.4 we do, let me check 7.4...seems to work, though I am on beta1
> > on this box.
>
> Hmm.  I do not see the pager used for \h in either version, though it
> does get used for \? ...

OK, turns out the '\h alter' code does a simple printf(), not a
PageOutput() and fprintf() to that pipe.  Various \h outputs are long,
including CREATE TABLE, GRANT, and ALTER TABLE.  ALTER itself is really
larger because it prints all the ALTER commands help.

The attached patch counts the number of newlines output by \h command,
and invokes the pager where appropriate.

This isn't a bug fix, so it will be kept for 7.5.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
Index: src/bin/psql/help.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/bin/psql/help.c,v
retrieving revision 1.78
diff -c -c -r1.78 help.c
*** src/bin/psql/help.c    10 Sep 2003 21:35:55 -0000    1.78
--- src/bin/psql/help.c    10 Sep 2003 22:12:39 -0000
***************
*** 303,322 ****
      {
          int            i;
          bool        help_found = false;
          size_t        len;
!
          /* don't care about trailing spaces */
          len = strlen(topic);
          while (topic[len - 1] == ' ')
              len--;

          for (i = 0; QL_HELP[i].cmd; i++)
          {
              if (strncasecmp(topic, QL_HELP[i].cmd, len) == 0 ||
                  strcmp(topic, "*") == 0)
              {
                  help_found = true;
!                 printf(_("Command:     %s\n"
                           "Description: %s\n"
                           "Syntax:\n%s\n\n"),
                       QL_HELP[i].cmd, QL_HELP[i].help, QL_HELP[i].syntax);
--- 303,343 ----
      {
          int            i;
          bool        help_found = false;
+         FILE       *output;
          size_t        len;
!         int            nl_count = 0;
!         char        *ch;
!
          /* don't care about trailing spaces */
          len = strlen(topic);
          while (topic[len - 1] == ' ')
              len--;

+         /* Count newlines for pager */
+         for (i = 0; QL_HELP[i].cmd; i++)
+         {
+             if (strncasecmp(topic, QL_HELP[i].cmd, len) == 0 ||
+                 strcmp(topic, "*") == 0)
+             {
+                 nl_count += 5;
+                 for (ch = QL_HELP[i].syntax; *ch != '\0'; ch++)
+                     if (*ch == '\n')
+                         nl_count++;
+                 /* If we have an exact match, exit.  Fixes \h SELECT */
+                 if (strcasecmp(topic, QL_HELP[i].cmd) == 0)
+                     break;
+             }
+         }
+
+         output = PageOutput(nl_count, pager);
+
          for (i = 0; QL_HELP[i].cmd; i++)
          {
              if (strncasecmp(topic, QL_HELP[i].cmd, len) == 0 ||
                  strcmp(topic, "*") == 0)
              {
                  help_found = true;
!                 fprintf(output, _("Command:     %s\n"
                           "Description: %s\n"
                           "Syntax:\n%s\n\n"),
                       QL_HELP[i].cmd, QL_HELP[i].help, QL_HELP[i].syntax);
***************
*** 327,333 ****
          }

          if (!help_found)
!             printf(_("No help available for \"%-.*s\".\nTry \\h with no arguments to see available help.\n"), (int)
len,topic); 
      }
  }

--- 348,363 ----
          }

          if (!help_found)
!             fprintf(output, _("No help available for \"%-.*s\".\nTry \\h with no arguments to see available
help.\n"),(int) len, topic); 
!
!         /* Only close if we used the pager */
!         if (output != stdout)
!         {
!             pclose(output);
! #ifndef WIN32
!             pqsignal(SIGPIPE, SIG_DFL);
! #endif
!         }
      }
  }

Bruce Momjian writes:

> OK, turns out the '\h alter' code does a simple printf(), not a
> PageOutput() and fprintf() to that pipe.  Various \h outputs are long,
> including CREATE TABLE, GRANT, and ALTER TABLE.  ALTER itself is really
> larger because it prints all the ALTER commands help.

They are long, but not not longer than a few pages, in which case it's
more convenient to use your terminals scrolling functionality.  It's a
different story when query output is thousands of lines long, in which
case you usually cannot scroll anymore.

--
Peter Eisentraut   peter_e@gmx.net

Peter Eisentraut wrote:
> Bruce Momjian writes:
>
> > OK, turns out the '\h alter' code does a simple printf(), not a
> > PageOutput() and fprintf() to that pipe.  Various \h outputs are long,
> > including CREATE TABLE, GRANT, and ALTER TABLE.  ALTER itself is really
> > larger because it prints all the ALTER commands help.
>
> They are long, but not not longer than a few pages, in which case it's
> more convenient to use your terminals scrolling functionality.  It's a
> different story when query output is thousands of lines long, in which
> case you usually cannot scroll anymore.

Yes, but our table output already pages if it exceeds the screen size,
so it seems we should be consistent, and if someone is on the console,
they might not have scroll-back, and are left with ^S, ^Q.  :-)

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073