Sender: Elvis Pranskevichus <elprans@gmail.com>
From: Elvis Pranskevichus <el@prans.net>
To: pgsql-hackers@postgresql.org
Subject: [PATCH] Allow anonymous rowtypes in function return column definition
Date: Thu, 06 Dec 2018 17:27:32 -0500
Message-ID: <11038447.kQ5A9Uj5xi@hammer.magicstack.net>
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Currently, the following query

    SELECT q.b = row(2)
    FROM unnest(ARRAY[row(1, row(2))]) AS q(a int, b record);

would fail with

    ERROR:  column "b" has pseudo-type record

This is due to CheckAttributeNamesTypes() being used on a function
coldeflist as if it was a real relation definition.  But in the context
of a query there seems to be no harm in allowing this, as other ways of
manipulating anonymous rowtypes work well, e.g.:

    SELECT (ARRAY[ROW(1, ROW(2))])[1];


                                Elvis

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From 873ecd6b31abc28c787f398d78ba2511c6e712a2 Mon Sep 17 00:00:00 2001
From: Elvis Pranskevichus <elvis@magic.io>
Date: Thu, 6 Dec 2018 17:16:28 -0500
Subject: [PATCH] Allow anonymous rowtypes in function return column definition

Currently, the following query

    SELECT q.b = row(2)
    FROM unnest(ARRAY[row(1, row(2))]) AS q(a int, b record);

would fail with

    ERROR:  column "b" has pseudo-type record

This is due to CheckAttributeNamesTypes() being used on a function
coldeflist as if it was a real relation definition.  But in the context
of a query there seems to be no harm in allowing this, as other ways of
manipulating anonymous rowtypes work well, e.g.:

    SELECT (ARRAY[ROW(1, ROW(2))])[1];
---
 src/backend/catalog/heap.c             | 23 +++++++++++++++--------
 src/backend/catalog/index.c            |  2 +-
 src/backend/commands/tablecmds.c       |  4 ++--
 src/backend/parser/parse_relation.c    |  2 +-
 src/include/catalog/heap.h             |  6 ++++--
 src/test/regress/expected/rowtypes.out |  7 +++++++
 src/test/regress/sql/rowtypes.sql      |  2 ++
 7 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 8c52a1543d..ab9cb600f1 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -412,7 +412,8 @@ heap_create(const char *relname,
  */
 void
 CheckAttributeNamesTypes(TupleDesc tupdesc, char relkind,
-						 bool allow_system_table_mods)
+						 bool allow_system_table_mods,
+						 bool allow_anonymous_records)
 {
 	int			i;
 	int			j;
@@ -471,7 +472,8 @@ CheckAttributeNamesTypes(TupleDesc tupdesc, char relkind,
 						   TupleDescAttr(tupdesc, i)->atttypid,
 						   TupleDescAttr(tupdesc, i)->attcollation,
 						   NIL, /* assume we're creating a new rowtype */
-						   allow_system_table_mods);
+						   allow_system_table_mods,
+						   allow_anonymous_records);
 	}
 }
 
@@ -494,7 +496,8 @@ void
 CheckAttributeType(const char *attname,
 				   Oid atttypid, Oid attcollation,
 				   List *containing_rowtypes,
-				   bool allow_system_table_mods)
+				   bool allow_system_table_mods,
+				   bool allow_anonymous_records)
 {
 	char		att_typtype = get_typtype(atttypid);
 	Oid			att_typelem;
@@ -507,7 +510,8 @@ CheckAttributeType(const char *attname,
 		 * catalogs (this allows creating pg_statistic and cloning it during
 		 * VACUUM FULL)
 		 */
-		if (atttypid != ANYARRAYOID || !allow_system_table_mods)
+		if (!((atttypid == ANYARRAYOID && allow_system_table_mods) ||
+				(atttypid == RECORDOID && allow_anonymous_records)))
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 					 errmsg("column \"%s\" has pseudo-type %s",
@@ -520,7 +524,8 @@ CheckAttributeType(const char *attname,
 		 */
 		CheckAttributeType(attname, getBaseType(atttypid), attcollation,
 						   containing_rowtypes,
-						   allow_system_table_mods);
+						   allow_system_table_mods,
+						   allow_anonymous_records);
 	}
 	else if (att_typtype == TYPTYPE_COMPOSITE)
 	{
@@ -558,7 +563,8 @@ CheckAttributeType(const char *attname,
 			CheckAttributeType(NameStr(attr->attname),
 							   attr->atttypid, attr->attcollation,
 							   containing_rowtypes,
-							   allow_system_table_mods);
+							   allow_system_table_mods,
+							   allow_anonymous_records);
 		}
 
 		relation_close(relation, AccessShareLock);
@@ -572,7 +578,8 @@ CheckAttributeType(const char *attname,
 		 */
 		CheckAttributeType(attname, att_typelem, attcollation,
 						   containing_rowtypes,
-						   allow_system_table_mods);
+						   allow_system_table_mods,
+						   allow_anonymous_records);
 	}
 
 	/*
@@ -1063,7 +1070,7 @@ heap_create_with_catalog(const char *relname,
 	 */
 	Assert(IsNormalProcessingMode() || IsBootstrapProcessingMode());
 
-	CheckAttributeNamesTypes(tupdesc, relkind, allow_system_table_mods);
+	CheckAttributeNamesTypes(tupdesc, relkind, allow_system_table_mods, false);
 
 	/*
 	 * This would fail later on anyway, if the relation already exists.  But
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 44625a507b..ac5a285be7 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -435,7 +435,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 			 */
 			CheckAttributeType(NameStr(to->attname),
 							   to->atttypid, to->attcollation,
-							   NIL, false);
+							   NIL, false, false);
 		}
 
 		/*
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 357c73073d..0a19209519 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -5488,7 +5488,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	/* make sure datatype is legal for a column */
 	CheckAttributeType(colDef->colname, typeOid, collOid,
 					   list_make1_oid(rel->rd_rel->reltype),
-					   false);
+					   false, false);
 
 	/* construct new attribute's pg_attribute entry */
 	attribute.attrelid = myrelid;
@@ -9126,7 +9126,7 @@ ATPrepAlterColumnType(List **wqueue,
 	/* make sure datatype is legal for a column */
 	CheckAttributeType(colName, targettype, targetcollid,
 					   list_make1_oid(rel->rd_rel->reltype),
-					   false);
+					   false, false);
 
 	if (tab->relkind == RELKIND_RELATION ||
 		tab->relkind == RELKIND_PARTITIONED_TABLE)
diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index bf5df26009..0f224e7718 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -1567,7 +1567,7 @@ addRangeTableEntryForFunction(ParseState *pstate,
 			 * Ensure that the coldeflist defines a legal set of names (no
 			 * duplicates) and datatypes (no pseudo-types, for instance).
 			 */
-			CheckAttributeNamesTypes(tupdesc, RELKIND_COMPOSITE_TYPE, false);
+			CheckAttributeNamesTypes(tupdesc, RELKIND_COMPOSITE_TYPE, false, true);
 		}
 		else
 			ereport(ERROR,
diff --git a/src/include/catalog/heap.h b/src/include/catalog/heap.h
index c5e40ff017..9ee4824af8 100644
--- a/src/include/catalog/heap.h
+++ b/src/include/catalog/heap.h
@@ -133,12 +133,14 @@ extern Form_pg_attribute SystemAttributeByName(const char *attname,
 					  bool relhasoids);
 
 extern void CheckAttributeNamesTypes(TupleDesc tupdesc, char relkind,
-						 bool allow_system_table_mods);
+						 bool allow_system_table_mods,
+						 bool allow_anonymous_records);
 
 extern void CheckAttributeType(const char *attname,
 				   Oid atttypid, Oid attcollation,
 				   List *containing_rowtypes,
-				   bool allow_system_table_mods);
+				   bool allow_system_table_mods,
+				   bool allow_anonymous_records);
 
 /* pg_partitioned_table catalog manipulation functions */
 extern void StorePartitionKey(Relation rel,
diff --git a/src/test/regress/expected/rowtypes.out b/src/test/regress/expected/rowtypes.out
index 30053d07df..0a98725d98 100644
--- a/src/test/regress/expected/rowtypes.out
+++ b/src/test/regress/expected/rowtypes.out
@@ -668,6 +668,13 @@ select row(1, '(1,2)')::testtype6 *<> row(1, '(1,3)')::testtype6;
 (1 row)
 
 drop type testtype1, testtype2, testtype3, testtype4, testtype5, testtype6;
+-- Test anonymous rowtype in coldeflist
+SELECT q.b = row(2) FROM unnest(ARRAY[row(1, row(2))]) AS q(a int, b record);
+ ?column? 
+----------
+ t
+(1 row)
+
 --
 -- Test case derived from bug #5716: check multiple uses of a rowtype result
 --
diff --git a/src/test/regress/sql/rowtypes.sql b/src/test/regress/sql/rowtypes.sql
index faf2e108d6..08d320426a 100644
--- a/src/test/regress/sql/rowtypes.sql
+++ b/src/test/regress/sql/rowtypes.sql
@@ -261,6 +261,8 @@ select row(1, '(1,2)')::testtype6 *<> row(1, '(1,3)')::testtype6;
 
 drop type testtype1, testtype2, testtype3, testtype4, testtype5, testtype6;
 
+-- Test anonymous rowtype in coldeflist
+SELECT q.b = row(2) FROM unnest(ARRAY[row(1, row(2))]) AS q(a int, b record);
 
 --
 -- Test case derived from bug #5716: check multiple uses of a rowtype result
-- 
2.19.2


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