Add citus_version(), analogous to PG's version()

This will provide the full project name (i.e. Citus/Citus Enterprise),
and the host system, compiler, and architecture word size.

I wanted to limit the number of copied files in 'config', so I added
only config.guess and call it manually, rather than using the macro
AC_CANONICAL_HOST, which requires several other files.

configure.in

@@ -89,6 +89,23 @@ SAVE_CFLAGS="$CFLAGS"
 AC_PROG_CC([$($PG_CONFIG --cc)])
 CFLAGS="$SAVE_CFLAGS"
 
+host_guess=`${SHELL} $srcdir/config/config.guess`
+
+# Create compiler version string
+if test x"$GCC" = x"yes" ; then
+  cc_string=`${CC} --version | sed q`
+  case $cc_string in [[A-Za-z]]*) ;; *) cc_string="GCC $cc_string";; esac
+elif test x"$SUN_STUDIO_CC" = x"yes" ; then
+  cc_string=`${CC} -V 2>&1 | sed q`
+else
+  cc_string=$CC
+fi
+
+AC_CHECK_SIZEOF([void *])
+
+AC_DEFINE_UNQUOTED(CITUS_VERSION_STR,
+                   ["$PACKAGE_NAME $CITUS_VERSION on $host_guess, compiled by $cc_string, `expr $ac_cv_sizeof_void_p \* 8`-bit"],
+                   [A string containing the version number, platform, and C compiler])
 
 # Locate source and build directory of the postgres we're building
 # against. Can't rely on either still being present, but e.g. optional

src/backend/distributed/Makefile

@@ -12,7 +12,7 @@ EXTVERSIONS = 5.0 5.0-1 5.0-2  \
 	6.1-1 6.1-2 6.1-3 6.1-4 6.1-5 6.1-6 6.1-7 6.1-8 6.1-9 6.1-10 6.1-11 6.1-12 6.1-13 6.1-14 6.1-15 6.1-16 6.1-17 \
 	6.2-1 6.2-2 6.2-3 6.2-4 \
 	7.0-1 7.0-2 7.0-3 7.0-4 7.0-5 7.0-6 7.0-7 7.0-8 7.0-9 7.0-10 7.0-11 7.0-12 7.0-13 7.0-14 7.0-15 \
-	7.1-1
+	7.1-1 7.1-2
 
 # All citus--*.sql files in the source directory
 DATA = $(patsubst $(citus_abs_srcdir)/%.sql,%.sql,$(wildcard $(citus_abs_srcdir)/$(EXTENSION)--*--*.sql))
@@ -172,6 +172,8 @@ $(EXTENSION)--7.0-15.sql: $(EXTENSION)--7.0-14.sql $(EXTENSION)--7.0-14--7.0-15.
 	cat $^ > $@
 $(EXTENSION)--7.1-1.sql: $(EXTENSION)--7.0-15.sql $(EXTENSION)--7.0-15--7.1-1.sql
 	cat $^ > $@
+$(EXTENSION)--7.1-2.sql: $(EXTENSION)--7.1-1.sql $(EXTENSION)--7.1-1--7.1-2.sql
+	cat $^ > $@
 
 NO_PGXS = 1
 

src/backend/distributed/citus--7.1-1--7.1-2.sql

@@ -0,0 +1,8 @@
+/* citus--7.1-1--7.1-2 */
+
+CREATE OR REPLACE FUNCTION pg_catalog.citus_version()
+    RETURNS text
+    LANGUAGE C STABLE STRICT
+    AS 'MODULE_PATHNAME', $$citus_version$$;
+COMMENT ON FUNCTION pg_catalog.citus_version()
+    IS 'Citus version string';

src/backend/distributed/citus.control

@@ -1,6 +1,6 @@
 # Citus extension
 comment = 'Citus distributed database'
-default_version = '7.1-1'
+default_version = '7.1-2'
 module_pathname = '$libdir/citus'
 relocatable = false
 schema = pg_catalog

src/backend/distributed/utils/citus_version.c

@@ -0,0 +1,26 @@
+/*-------------------------------------------------------------------------
+ *
+ * citus_version.c
+ *
+ * This file contains functions for displaying the Citus version string
+ *
+ * Copyright (c) 2017, Citus Data, Inc.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "citus_version.h"
+#include "utils/builtins.h"
+
+
+/* exports for SQL callable functions */
+PG_FUNCTION_INFO_V1(citus_version);
+
+
+Datum
+citus_version(PG_FUNCTION_ARGS)
+{
+	PG_RETURN_TEXT_P(cstring_to_text(CITUS_VERSION_STR));
+}

src/include/citus_config.h.in

@@ -22,6 +22,9 @@
 /* Citus version as a number */
 #undef CITUS_VERSION_NUM
 
+/* A string containing the version number, platform, and C compiler */
+#undef CITUS_VERSION_STR
+
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
@@ -70,5 +73,8 @@
 /* Define to the version of this package. */
 #undef PACKAGE_VERSION
 
+/* The size of `void *', as computed by sizeof. */
+#undef SIZEOF_VOID_P
+
 /* Define to 1 if you have the ANSI C header files. */
 #undef STDC_HEADERS

src/include/citus_version.h.in

@@ -12,5 +12,8 @@
 /* Citus version as a number */
 #undef CITUS_VERSION_NUM
 
+/* A string containing the version number, platform, and C compiler */
+#undef CITUS_VERSION_STR
+
 /* Define to 1 if you have the `curl' library (-lcurl). */
 #undef HAVE_LIBCURL