Re: [BUGS] PSQL commands not backwards-compatible

Josh Berkus wrote:
> Tom,
>
> > They've been broken on a fairly regular basis in past releases.
> > Certainly 7.3 broke every single one because of the addition of
> > schema syntax ...
>
> Yeah, and we warned people about it, as I recall.   Also, we had about 25x
> less users then.   I think we should put something in the release notes:
>
> WARNING: 8.1's "psql" is not completely backwards-compatible with previous
> versions of PostgreSQL.

Here is a patch that will print out (in interactive mode only) a warning
message if a newer client connects to an older major numbered server.

--
  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/startup.c
===================================================================
RCS file: /cvsroot/pgsql/src/bin/psql/startup.c,v
retrieving revision 1.120
diff -c -c -r1.120 startup.c
*** src/bin/psql/startup.c    25 Jul 2005 17:17:41 -0000    1.120
--- src/bin/psql/startup.c    31 Aug 2005 02:19:12 -0000
***************
*** 8,13 ****
--- 8,14 ----
  #include "postgres_fe.h"

  #include <sys/types.h>
+ #include <math.h>

  #ifndef WIN32
  #include <unistd.h>
***************
*** 312,317 ****
--- 313,325 ----

          if (!QUIET() && !pset.notty)
          {
+             if (pset.sversion / 100 < atoi(PG_VERSION) * 100 +
+                 (strchr(PG_VERSION, '.')[1] - '0'))
+                 printf(_("You are connected to a server with an earlier major version\n"
+                          "than your %s client.  Informational backslash commands, like \\d,\n"
+                          "might not work properly.\n\n"),
+                          pset.progname);
+
              printf(_("Welcome to %s %s, the PostgreSQL interactive terminal.\n\n"
                             "Type:  \\copyright for distribution terms\n"
                             "       \\h for help with SQL commands\n"