Drop support for Python 2.3

There is no specific reason for this right now, but keeping support for
old Python versions around indefinitely increases the maintenance
burden.  The oldest supported Python version is now Python 2.4, which is
still shipped in RHEL/CentOS 5 by default.

In configure, add a check for the required Python version and give a
friendly error message for an old version, instead of relying on an
obscure build error later on.

config/python.m4

@@ -31,6 +31,7 @@ else
 fi
 AC_MSG_CHECKING([Python configuration directory])
 python_majorversion=`${PYTHON} -c "import sys; print(sys.version[[0]])"`
+python_minorversion=`${PYTHON} -c "import sys; print(sys.version[[2]])"`
 python_version=`${PYTHON} -c "import sys; print(sys.version[[:3]])"`
 python_configdir=`${PYTHON} -c "import distutils.sysconfig; print(' '.join(filter(None,distutils.sysconfig.get_config_vars('LIBPL'))))"`
 AC_MSG_RESULT([$python_configdir])

configure

@@ -7588,6 +7588,7 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking Python configuration directory" >&5
 $as_echo_n "checking Python configuration directory... " >&6; }
 python_majorversion=`${PYTHON} -c "import sys; print(sys.version[0])"`
+python_minorversion=`${PYTHON} -c "import sys; print(sys.version[2])"`
 python_version=`${PYTHON} -c "import sys; print(sys.version[:3])"`
 python_configdir=`${PYTHON} -c "import distutils.sysconfig; print(' '.join(filter(None,distutils.sysconfig.get_config_vars('LIBPL'))))"`
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $python_configdir" >&5
@@ -7698,6 +7699,9 @@ $as_echo "${python_libspec} ${python_additional_libs}" >&6; }
 
 
 
+  if test "$python_majorversion" -lt 3 -a "$python_minorversion" -lt 4; then
+    as_fn_error $? "Python version $python_version is too old (version 2.4 or later is required)" "$LINENO" 5
+  fi
 fi
 
 if test "$cross_compiling" = yes && test -z "$with_system_tzdata"; then

configure.in

@@ -927,6 +927,9 @@ fi
 if test "$with_python" = yes; then
   PGAC_PATH_PYTHON
   PGAC_CHECK_PYTHON_EMBED_SETUP
+  if test "$python_majorversion" -lt 3 -a "$python_minorversion" -lt 4; then
+    AC_MSG_ERROR([Python version $python_version is too old (version 2.4 or later is required)])
+  fi
 fi
 
 if test "$cross_compiling" = yes && test -z "$with_system_tzdata"; then

contrib/hstore_plpython/expected/hstore_plpython.out

@@ -6,9 +6,7 @@ LANGUAGE plpythonu
 TRANSFORM FOR TYPE hstore
 AS $$
 assert isinstance(val, dict)
-i = list(val.items())
-i.sort()
-plpy.info(i)
+plpy.info(sorted(val.items()))
 return len(val)
 $$;
 SELECT test1('aa=>bb, cc=>NULL'::hstore);
@@ -24,9 +22,7 @@ LANGUAGE plpython2u
 TRANSFORM FOR TYPE hstore
 AS $$
 assert isinstance(val, dict)
-i = list(val.items())
-i.sort()
-plpy.info(i)
+plpy.info(sorted(val.items()))
 return len(val)
 $$;
 SELECT test1n('aa=>bb, cc=>NULL'::hstore);

contrib/hstore_plpython/sql/hstore_plpython.sql

@@ -7,9 +7,7 @@ LANGUAGE plpythonu
 TRANSFORM FOR TYPE hstore
 AS $$
 assert isinstance(val, dict)
-i = list(val.items())
-i.sort()
-plpy.info(i)
+plpy.info(sorted(val.items()))
 return len(val)
 $$;
 
@@ -22,9 +20,7 @@ LANGUAGE plpython2u
 TRANSFORM FOR TYPE hstore
 AS $$
 assert isinstance(val, dict)
-i = list(val.items())
-i.sort()
-plpy.info(i)
+plpy.info(sorted(val.items()))
 return len(val)
 $$;
 

doc/src/sgml/installation.sgml

@@ -193,11 +193,7 @@ su - postgres
       language, you need a <productname>Python</productname>
       installation with the header files and
       the <application>distutils</application> module.  The minimum
-      required version is <productname>Python</productname> 2.3.
-      (To work with function arguments of type <type>numeric</>, a 2.3.x
-      installation must include the separately-available <filename>cdecimal</>
-      module; note the <application>PL/Python</> regression tests
-      will not pass if that is missing.)
+      required version is <productname>Python</productname> 2.4.
       <productname>Python 3</productname> is supported if it's
       version 3.1 or later; but see
       <![%standalone-include[the <application>PL/Python</> documentation]]>

src/pl/plpython/expected/plpython_ereport.out

@@ -94,26 +94,22 @@ kwargs = {
     "column_name": _column_name, "datatype_name": _datatype_name,
     "constraint_name": _constraint_name
 }
-# ignore None values - should work on Python2.3
-dict = {}
-for k in kwargs:
-    if kwargs[k] is not None:
-        dict[k] = kwargs[k]
-plpy.error(**dict)
+# ignore None values
+plpy.error(**dict((k, v) for k, v in iter(kwargs.items()) if v))
 $$ LANGUAGE plpythonu;
 SELECT raise_exception('hello', 'world');
 ERROR:  plpy.Error: hello
 DETAIL:  world
 CONTEXT:  Traceback (most recent call last):
-  PL/Python function "raise_exception", line 13, in <module>
-    plpy.error(**dict)
+  PL/Python function "raise_exception", line 9, in <module>
+    plpy.error(**dict((k, v) for k, v in iter(kwargs.items()) if v))
 PL/Python function "raise_exception"
 SELECT raise_exception('message text', 'detail text', _sqlstate => 'YY333');
 ERROR:  plpy.Error: message text
 DETAIL:  detail text
 CONTEXT:  Traceback (most recent call last):
-  PL/Python function "raise_exception", line 13, in <module>
-    plpy.error(**dict)
+  PL/Python function "raise_exception", line 9, in <module>
+    plpy.error(**dict((k, v) for k, v in iter(kwargs.items()) if v))
 PL/Python function "raise_exception"
 SELECT raise_exception(_message => 'message text',
                        _detail => 'detail text',
@@ -128,8 +124,8 @@ ERROR:  plpy.Error: message text
 DETAIL:  detail text
 HINT:  hint text
 CONTEXT:  Traceback (most recent call last):
-  PL/Python function "raise_exception", line 13, in <module>
-    plpy.error(**dict)
+  PL/Python function "raise_exception", line 9, in <module>
+    plpy.error(**dict((k, v) for k, v in iter(kwargs.items()) if v))
 PL/Python function "raise_exception"
 SELECT raise_exception(_message => 'message text',
                        _hint => 'hint text',
@@ -139,8 +135,8 @@ SELECT raise_exception(_message => 'message text',
 ERROR:  plpy.Error: message text
 HINT:  hint text
 CONTEXT:  Traceback (most recent call last):
-  PL/Python function "raise_exception", line 13, in <module>
-    plpy.error(**dict)
+  PL/Python function "raise_exception", line 9, in <module>
+    plpy.error(**dict((k, v) for k, v in iter(kwargs.items()) if v))
 PL/Python function "raise_exception"
 DO $$
 DECLARE

src/pl/plpython/plpy_typeio.c

@@ -521,15 +521,9 @@ PLy_input_datum_func2(PLyDatumToOb *arg, MemoryContext arg_mcxt, Oid typeOid, He
 static PyObject *
 PLyBool_FromBool(PLyDatumToOb *arg, Datum d)
 {
-	/*
-	 * We would like to use Py_RETURN_TRUE and Py_RETURN_FALSE here for
-	 * generating SQL from trigger functions, but those are only supported in
-	 * Python >= 2.4, and we support older versions.
-	 * http://docs.python.org/api/boolObjects.html
-	 */
 	if (DatumGetBool(d))
-		return PyBool_FromLong(1);
-	return PyBool_FromLong(0);
+		Py_RETURN_TRUE;
+	Py_RETURN_FALSE;
 }
 
 static PyObject *

src/pl/plpython/sql/plpython_ereport.sql

@@ -55,12 +55,8 @@ kwargs = {
     "column_name": _column_name, "datatype_name": _datatype_name,
     "constraint_name": _constraint_name
 }
-# ignore None values - should work on Python2.3
-dict = {}
-for k in kwargs:
-    if kwargs[k] is not None:
-        dict[k] = kwargs[k]
-plpy.error(**dict)
+# ignore None values
+plpy.error(**dict((k, v) for k, v in iter(kwargs.items()) if v))
 $$ LANGUAGE plpythonu;
 
 SELECT raise_exception('hello', 'world');