Fix type-checking of RECORD-returning functions in FROM, redux.

Commit 2ed8f9a01 intended to institute a policy that if a
RangeTblFunction has a coldeflist, then the function return type is
certainly RECORD, and we should use the coldeflist as the source of
truth about what the columns of the record type are.  When the
original function has been folded to a constant, inspection of the
constant might give a different answer.  This situation will lead to
a tuple-type-mismatch error at execution, but up until that point we
need to consistently believe the coldeflist, or we'll have problems
from different bits of code reaching different conclusions.

expandRTE didn't get that memo though, and would try to produce a
tupdesc based on the constant in this situation, leading to an
assertion failure.  (Desultory testing suggests that non-assert
builds often manage to give the expected error, although I also
saw a "cache lookup failed for type 0" error, and it seems at
least possible that a crash could happen.)

Some other callers of get_expr_result_type and get_expr_result_tupdesc
were also being incautious about this.  While none of them seem to
have actual bugs, they're working harder than necessary in this case,
besides which it seems safest to have an explicit policy of not using
those functions on an RTE with a coldeflist.  Adjust the code
accordingly, and add commentary to funcapi.c about this policy.

Also fix an obsolete comment that claimed "get_expr_result_type()
doesn't know how to extract type info from a RECORD constant".
That hasn't been true since commit d57534740.

Per bug #18422 from Alexander Lakhin.
As with the previous commit, back-patch to all supported branches.

Discussion: https://postgr.es/m/18422-89ca86c8eac5246d@postgresql.org

diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 388694e7095093a9f1b9d1fa42943255c758dbae..541c581ec48b9581551f1d85dbdeabbfbab90d36 100644 (file)
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -1736,6 +1736,10 @@ pull_up_constant_function(PlannerInfo *root, Node *jtnode,
    if (rtf->funccolcount != 1)
        return jtnode;          /* definitely composite */
 
+   /* If it has a coldeflist, it certainly returns RECORD */
+   if (rtf->funccolnames != NIL)
+       return jtnode;          /* must be a one-column RECORD type */
+
    functypclass = get_expr_result_type(rtf->funcexpr,
                                        &funcrettype,
                                        &tupdesc);

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 85532cab031e36a1089d9909addab324352f53da..0f6f7eb79532900e613f566b859aadd36135e5bf 100644 (file)
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -4346,12 +4346,11 @@ evaluate_function(Oid funcid, Oid result_type, int32 result_typmod,
     * Can't simplify if it returns RECORD.  The immediate problem is that it
     * will be needing an expected tupdesc which we can't supply here.
     *
-    * In the case where it has OUT parameters, it could get by without an
-    * expected tupdesc, but we still have issues: get_expr_result_type()
-    * doesn't know how to extract type info from a RECORD constant, and in
-    * the case of a NULL function result there doesn't seem to be any clean
-    * way to fix that.  In view of the likelihood of there being still other
-    * gotchas, seems best to leave the function call unreduced.
+    * In the case where it has OUT parameters, we could build an expected
+    * tupdesc from those, but there may be other gotchas lurking.  In
+    * particular, if the function were to return NULL, we would produce a
+    * null constant with no remaining indication of which concrete record
+    * type it is.  For now, seems best to leave the function call unreduced.
     */
    if (funcform->prorettype == RECORDOID)
        return NULL;

diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index 7d40f4ce372ca0083f6a4e918b779eda69373fa2..0ca5bdea60f4864cbd3a248ba753a58973d7cf6b 100644 (file)
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -2627,12 +2627,17 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
                {
                    RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
                    TypeFuncClass functypclass;
-                   Oid         funcrettype;
-                   TupleDesc   tupdesc;
+                   Oid         funcrettype = InvalidOid;
+                   TupleDesc   tupdesc = NULL;
+
+                   /* If it has a coldeflist, it returns RECORD */
+                   if (rtfunc->funccolnames != NIL)
+                       functypclass = TYPEFUNC_RECORD;
+                   else
+                       functypclass = get_expr_result_type(rtfunc->funcexpr,
+                                                           &funcrettype,
+                                                           &tupdesc);
 
-                   functypclass = get_expr_result_type(rtfunc->funcexpr,
-                                                       &funcrettype,
-                                                       &tupdesc);
                    if (functypclass == TYPEFUNC_COMPOSITE ||
                        functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
                    {
@@ -3242,6 +3247,10 @@ get_rte_attribute_is_dropped(RangeTblEntry *rte, AttrNumber attnum)
                    {
                        TupleDesc   tupdesc;
 
+                       /* If it has a coldeflist, it returns RECORD */
+                       if (rtfunc->funccolnames != NIL)
+                           return false;   /* can't have any dropped columns */
+
                        tupdesc = get_expr_result_tupdesc(rtfunc->funcexpr,
                                                          true);
                        if (tupdesc)

diff --git a/src/backend/utils/fmgr/funcapi.c b/src/backend/utils/fmgr/funcapi.c
index ac1c75d62be27fbfa34cc120021b5532e7b96571..4d3f8eb93d1f4ad0bc1690fb3295773a919f0e14 100644 (file)
--- a/src/backend/utils/fmgr/funcapi.c
+++ b/src/backend/utils/fmgr/funcapi.c
@@ -216,6 +216,13 @@ get_call_result_type(FunctionCallInfo fcinfo,
 /*
  * get_expr_result_type
  *     As above, but work from a calling expression node tree
+ *
+ * Beware of using this on the funcexpr of a RTE that has a coldeflist.
+ * The correct conclusion in such cases is always that the function returns
+ * RECORD with the columns defined by the coldeflist fields (funccolnames etc).
+ * If it does not, it's the executor's responsibility to catch the discrepancy
+ * at runtime; but code processing the query in advance of that point might
+ * come to inconsistent conclusions if it checks the actual expression.
  */
 TypeFuncClass
 get_expr_result_type(Node *expr,
@@ -466,7 +473,8 @@ internal_get_result_type(Oid funcid,
  * if noError is true, else throws error.
  *
  * This is a simpler version of get_expr_result_type() for use when the caller
- * is only interested in determinate rowtype results.
+ * is only interested in determinate rowtype results.  As with that function,
+ * beware of using this on the funcexpr of a RTE that has a coldeflist.
  */
 TupleDesc
 get_expr_result_tupdesc(Node *expr, bool noError)

diff --git a/src/test/regress/expected/rangefuncs.out b/src/test/regress/expected/rangefuncs.out
index 2b416fec6ff329274bd9474ffb0b7f672f0e4ad6..88ca7523c4ab7533f7f98856d0b95f9c358e800d 100644 (file)
--- a/src/test/regress/expected/rangefuncs.out
+++ b/src/test/regress/expected/rangefuncs.out
@@ -2445,3 +2445,6 @@ with a(b) as (values (row(1,2,3)))
 select * from a, coalesce(b) as c(d int, e int, f float);  -- fail
 ERROR:  function return row and query-specified return row do not match
 DETAIL:  Returned type integer at ordinal position 3, but query expects double precision.
+select * from int8_tbl, coalesce(row(1)) as (a int, b int);  -- fail
+ERROR:  function return row and query-specified return row do not match
+DETAIL:  Returned row contains 1 attribute, but query expects 2.

diff --git a/src/test/regress/sql/rangefuncs.sql b/src/test/regress/sql/rangefuncs.sql
index d9a8c161180140c9896a92c415ab2897d285181b..4c42921d73f5669d637783fb2ed1e390a24a8871 100644 (file)
--- a/src/test/regress/sql/rangefuncs.sql
+++ b/src/test/regress/sql/rangefuncs.sql
@@ -786,3 +786,4 @@ with a(b) as (values (row(1,2,3)))
 select * from a, coalesce(b) as c(d int, e int, f int, g int);  -- fail
 with a(b) as (values (row(1,2,3)))
 select * from a, coalesce(b) as c(d int, e int, f float);  -- fail
+select * from int8_tbl, coalesce(row(1)) as (a int, b int);  -- fail