Fix recursive RECORD-returning plpython functions.

If we recursed to a new call of the same function, with a different
coldeflist (AS clause), it would fail because the inner call would
overwrite the outer call's idea of what to return.  This is vaguely
like 1d2fe56e4 and c5bec5426, but it's not due to any API decisions:
it's just that we computed the actual output rowtype at the start of
the call, and saved it in the per-procedure data structure.  We can
fix it at basically zero cost by doing the computation at the end
of each call instead of the start.

It's not clear that there's any real-world use-case for such a
function, but given that it doesn't cost anything to fix,
it'd be silly not to.

Per report from Andreas Karlsson.  Back-patch to all supported
branches.

Discussion: https://postgr.es/m/1651a46d-3c15-4028-a8c1-d74937b54e19@proxel.se

diff --git a/src/pl/plpython/expected/plpython_composite.out b/src/pl/plpython/expected/plpython_composite.out
index bb101e07d539fa5bda35c9a8a10b177ab74c9955..674af93ddcfe07209865443d112f43f5b11f3d65 100644 (file)
--- a/src/pl/plpython/expected/plpython_composite.out
+++ b/src/pl/plpython/expected/plpython_composite.out
@@ -569,6 +569,20 @@ SELECT * FROM return_record_2('v3') AS (v1 int, v2 int, v3 int);
   1 |  2 |  3
 (1 row)
 
+-- recursion with a different inner result type didn't use to work
+CREATE FUNCTION return_record_3(t text) RETURNS record AS $$
+if t == "text":
+     plpy.execute("SELECT * FROM return_record_3('int') AS (a int)");
+     return { "a": "x" }
+elif t == "int":
+     return { "a": 1 }
+$$ LANGUAGE plpython3u;
+SELECT * FROM return_record_3('text') AS (a text);
+ a 
+---
+ x
+(1 row)
+
 -- multi-dimensional array of composite types.
 CREATE FUNCTION composite_type_as_list()  RETURNS type_record[] AS $$
   return [[('first', 1), ('second', 1)], [('first', 2), ('second', 2)], [('first', 3), ('second', 3)]];

diff --git a/src/pl/plpython/plpy_exec.c b/src/pl/plpython/plpy_exec.c
index 9553c72e5eebe35255e74129ddf4ed02cb00e6bc..a7f7f6c553de0fcb38914c5df5bd951e6d82fbdc 100644 (file)
--- a/src/pl/plpython/plpy_exec.c
+++ b/src/pl/plpython/plpy_exec.c
@@ -231,7 +231,23 @@ PLy_exec_function(FunctionCallInfo fcinfo, PLyProcedure *proc)
        }
        else
        {
-           /* Normal conversion of result */
+           /*
+            * Normal conversion of result.  However, if the result is of type
+            * RECORD, we have to set up for that each time through, since it
+            * might be different from last time.
+            */
+           if (proc->result.typoid == RECORDOID)
+           {
+               TupleDesc   desc;
+
+               if (get_call_result_type(fcinfo, NULL, &desc) != TYPEFUNC_COMPOSITE)
+                   ereport(ERROR,
+                           (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                            errmsg("function returning record called in context "
+                                   "that cannot accept type record")));
+               PLy_output_setup_record(&proc->result, desc, proc);
+           }
+
            rv = PLy_output_convert(&proc->result, plrv,
                                    &fcinfo->isnull);
        }
@@ -458,21 +474,6 @@ PLy_function_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc)
                PLy_elog(ERROR, "PyDict_SetItemString() failed, while setting up arguments");
            arg = NULL;
        }
-
-       /* Set up output conversion for functions returning RECORD */
-       if (proc->result.typoid == RECORDOID)
-       {
-           TupleDesc   desc;
-
-           if (get_call_result_type(fcinfo, NULL, &desc) != TYPEFUNC_COMPOSITE)
-               ereport(ERROR,
-                       (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                        errmsg("function returning record called in context "
-                               "that cannot accept type record")));
-
-           /* cache the output conversion functions */
-           PLy_output_setup_record(&proc->result, desc, proc);
-       }
    }
    PG_CATCH();
    {

diff --git a/src/pl/plpython/sql/plpython_composite.sql b/src/pl/plpython/sql/plpython_composite.sql
index 21757701cc13d0a65dc77cde881ccd0bf9fed43a..1bb9b83b7191eb3d9f967821d0c0b9d311b9eff6 100644 (file)
--- a/src/pl/plpython/sql/plpython_composite.sql
+++ b/src/pl/plpython/sql/plpython_composite.sql
@@ -208,6 +208,17 @@ SELECT * FROM return_record_2('v4') AS (v1 int, v3 int, v2 int);
 SELECT * FROM return_record_2('v3') AS (v1 int, v3 int, v2 int);
 SELECT * FROM return_record_2('v3') AS (v1 int, v2 int, v3 int);
 
+-- recursion with a different inner result type didn't use to work
+CREATE FUNCTION return_record_3(t text) RETURNS record AS $$
+if t == "text":
+     plpy.execute("SELECT * FROM return_record_3('int') AS (a int)");
+     return { "a": "x" }
+elif t == "int":
+     return { "a": 1 }
+$$ LANGUAGE plpython3u;
+
+SELECT * FROM return_record_3('text') AS (a text);
+
 -- multi-dimensional array of composite types.
 CREATE FUNCTION composite_type_as_list()  RETURNS type_record[] AS $$
   return [[('first', 1), ('second', 1)], [('first', 2), ('second', 2)], [('first', 3), ('second', 3)]];