Add psql variables showing server version and psql version.

We already had a psql variable VERSION that shows the verbose form of
psql's own version.  Add VERSION_NAME to show the short form (e.g.,
"11devel") and VERSION_NUM to show the numeric form (e.g., 110000).
Also add SERVER_VERSION_NAME and SERVER_VERSION_NUM to show the short and
numeric forms of the server's version.  (We'd probably add SERVER_VERSION
with the verbose string if it were readily available; but adding another
network round trip to get it seems too expensive.)

The numeric forms, in particular, are expected to be useful for scripting
purposes, now that psql can do conditional tests.

Fabien Coelho, reviewed by Pavel Stehule

Discussion: https://postgr.es/m/alpine.DEB.2.20.1704020917220.4632@lancre

1 files changed, 19 insertions, 0 deletions

diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 96f3a402a40..4283bf35af4 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -3337,6 +3337,9 @@ checkWin32Codepage(void)
 void
 SyncVariables(void)
 {
+	char		vbuf[32];
+	const char *server_version;
+
 	/* get stuff from connection */
 	pset.encoding = PQclientEncoding(pset.db);
 	pset.popt.topt.encoding = pset.encoding;
@@ -3348,6 +3351,20 @@ SyncVariables(void)
 	SetVariable(pset.vars, "PORT", PQport(pset.db));
 	SetVariable(pset.vars, "ENCODING", pg_encoding_to_char(pset.encoding));
 
+	/* this bit should match connection_warnings(): */
+	/* Try to get full text form of version, might include "devel" etc */
+	server_version = PQparameterStatus(pset.db, "server_version");
+	/* Otherwise fall back on pset.sversion */
+	if (!server_version)
+	{
+		formatPGVersionNumber(pset.sversion, true, vbuf, sizeof(vbuf));
+		server_version = vbuf;
+	}
+	SetVariable(pset.vars, "SERVER_VERSION_NAME", server_version);
+
+	snprintf(vbuf, sizeof(vbuf), "%d", pset.sversion);
+	SetVariable(pset.vars, "SERVER_VERSION_NUM", vbuf);
+
 	/* send stuff to it, too */
 	PQsetErrorVerbosity(pset.db, pset.verbosity);
 	PQsetErrorContextVisibility(pset.db, pset.show_context);
@@ -3366,6 +3383,8 @@ UnsyncVariables(void)
 	SetVariable(pset.vars, "HOST", NULL);
 	SetVariable(pset.vars, "PORT", NULL);
 	SetVariable(pset.vars, "ENCODING", NULL);
+	SetVariable(pset.vars, "SERVER_VERSION_NAME", NULL);
+	SetVariable(pset.vars, "SERVER_VERSION_NUM", NULL);
 }