PL/Python: Avoid lossiness in float conversion

PL/Python uses str() to convert Python values back to PostgreSQL, but
str() is lossy for float values, so use repr() instead in that case.

Author: Marko Kreen 

diff --git a/src/pl/plpython/expected/plpython_types.out b/src/pl/plpython/expected/plpython_types.out
index 61d800b57a2b3f20d817478caf61595070219a00..17057a543d2b7f418a3b27a3558292807cf33c81 100644 (file)
--- a/src/pl/plpython/expected/plpython_types.out
+++ b/src/pl/plpython/expected/plpython_types.out
@@ -354,6 +354,14 @@ CONTEXT:  PL/Python function "test_type_conversion_float8"
                             
 (1 row)
 
+SELECT * FROM test_type_conversion_float8(100100100.654321);
+INFO:  (100100100.654321, )
+CONTEXT:  PL/Python function "test_type_conversion_float8"
+ test_type_conversion_float8 
+-----------------------------
+            100100100.654321
+(1 row)
+
 CREATE FUNCTION test_type_conversion_oid(x oid) RETURNS oid AS $$
 plpy.info(x, type(x))
 return x

diff --git a/src/pl/plpython/plpy_typeio.c b/src/pl/plpython/plpy_typeio.c
index 524534e613ded0928fc33bac83c162bf82df0e76..8c70c7c9783c7900b5dbcee2d971e3ad3c88a443 100644 (file)
--- a/src/pl/plpython/plpy_typeio.c
+++ b/src/pl/plpython/plpy_typeio.c
@@ -760,6 +760,18 @@ PLyObject_ToDatum(PLyObToDatum *arg, int32 typmod, PyObject *plrv)
 
    if (PyUnicode_Check(plrv))
        plrv_bo = PLyUnicode_Bytes(plrv);
+   else if (PyFloat_Check(plrv))
+   {
+       /* use repr() for floats, str() is lossy */
+#if PY_MAJOR_VERSION >= 3
+       PyObject   *s = PyObject_Repr(plrv);
+
+       plrv_bo = PLyUnicode_Bytes(s);
+       Py_XDECREF(s);
+#else
+       plrv_bo = PyObject_Repr(plrv);
+#endif
+   }
    else
    {
 #if PY_MAJOR_VERSION >= 3

diff --git a/src/pl/plpython/sql/plpython_types.sql b/src/pl/plpython/sql/plpython_types.sql
index d9d0db66bccf5ec4c2fc9ff698a8bfe1eaa6e6e8..19d920d3c7ba6471168ae23e406d35f04104f39b 100644 (file)
--- a/src/pl/plpython/sql/plpython_types.sql
+++ b/src/pl/plpython/sql/plpython_types.sql
@@ -122,6 +122,7 @@ SELECT * FROM test_type_conversion_float8(100);
 SELECT * FROM test_type_conversion_float8(-100);
 SELECT * FROM test_type_conversion_float8(5000000000.5);
 SELECT * FROM test_type_conversion_float8(null);
+SELECT * FROM test_type_conversion_float8(100100100.654321);
 
 
 CREATE FUNCTION test_type_conversion_oid(x oid) RETURNS oid AS $$