Delete a variable if an error occurs during its creation

Author: CherkashinSergey

expected/pg_variables_trans.out

@@ -1854,6 +1854,11 @@ SELECT pgv_insert('package', 'errs',row(1), true);
 
 (1 row)
 
+-- Variable should not exists in case when error occurs during creation
+SELECT pgv_insert('vars4', 'r1', row('str1', 'str1'));
+ERROR:  could not identify a hash function for type unknown
+SELECT pgv_select('vars4', 'r1', 0);
+ERROR:  unrecognized variable "r1"
 SELECT pgv_free();
  pgv_free 
 ----------

pg_variables.c

@@ -68,7 +68,6 @@ static void copyValue(VarState *src, VarState *dest, Variable *destVar);
 static void freeValue(VarState *varstate, Oid typid);
 static void removeState(TransObject *object, TransObjectType type,
 						TransState *stateToDelete);
-static void removeObject(TransObject *object, TransObjectType type);
 static bool isObjectChangedInCurrentTrans(TransObject *object);
 static bool isObjectChangedInUpperTrans(TransObject *object);
 
@@ -1626,13 +1625,14 @@ copyValue(VarState *src, VarState *dest, Variable *destVar)
 static void
 freeValue(VarState *varstate, Oid typid)
 {
-	if (typid == RECORDOID)
+	if (typid == RECORDOID && varstate->value.record.hctx)
 	{
 		/* All records will be freed */
 		MemoryContextDelete(varstate->value.record.hctx);
 	}
 	else if (varstate->value.scalar.typbyval == false &&
-			 varstate->value.scalar.is_null == false)
+			 varstate->value.scalar.is_null == false &&
+			 varstate->value.scalar.value)
 	{
 		pfree(DatumGetPointer(varstate->value.scalar.value));
 	}
@@ -1651,7 +1651,8 @@ removeState(TransObject *object, TransObjectType type, TransState *stateToDelete
 	pfree(stateToDelete);
 }
 
-static void
+/* Remove package or variable (either transactional or regular) */
+void
 removeObject(TransObject *object, TransObjectType type)
 {
 	bool		found;
@@ -1672,7 +1673,9 @@ removeObject(TransObject *object, TransObjectType type)
 		hash = packagesHash;
 	}
 	else
-		hash = ((Variable *) object)->package->varHashTransact;
+		hash = ((Variable *) object)->is_transactional ?
+			   ((Variable *) object)->package->varHashTransact :
+			   ((Variable *) object)->package->varHashRegular;
 
 	/* Remove all object's states */
 	while (!dlist_is_empty(&object->states))

pg_variables.h

@@ -155,6 +155,7 @@ extern void check_record_key(Variable *variable, Oid typid);
 extern void insert_record(Variable *variable, HeapTupleHeader tupleHeader);
 extern bool update_record(Variable *variable, HeapTupleHeader tupleHeader);
 extern bool delete_record(Variable *variable, Datum value, bool is_null);
+extern void removeObject(TransObject *object, TransObjectType type);
 
 #define GetActualState(object) \
 	(dlist_head_element(TransState, node, &((TransObject *) object)->states))

pg_variables_record.c

@@ -81,17 +81,29 @@ init_record(RecordVar *record, TupleDesc tupdesc, Variable *variable)
 								 TYPECACHE_HASH_PROC_FINFO |
 								 TYPECACHE_CMP_PROC_FINFO);
 
+	/*
+	 * In case something went wrong, you need to roll back the changes before
+	 * completing the transaction, because the variable may be regular
+	 * and not present in list of changed vars.
+	 */
 	if (!OidIsValid(typentry->hash_proc_finfo.fn_oid))
+	{
+		/* At this point variable is just created, so we simply remove it. */
+		removeObject(&variable->transObject, TRANS_VARIABLE);
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_FUNCTION),
 				 errmsg("could not identify a hash function for type %s",
 						format_type_be(keyid))));
+	}
 
 	if (!OidIsValid(typentry->cmp_proc_finfo.fn_oid))
+	{
+		removeObject(&variable->transObject, TRANS_VARIABLE);
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_FUNCTION),
 				 errmsg("could not identify a matching function for type %s",
 						format_type_be(keyid))));
+	}
 
 	/* Initialize the record */
 

sql/pg_variables_trans.sql

@@ -467,4 +467,8 @@ SELECT pgv_insert('package', 'errs',row(n), true)
 FROM generate_series(1,5) AS gs(n) WHERE 1.0/(n-3)<>0;
 SELECT pgv_insert('package', 'errs',row(1), true);
 
+-- Variable should not exists in case when error occurs during creation
+SELECT pgv_insert('vars4', 'r1', row('str1', 'str1'));
+SELECT pgv_select('vars4', 'r1', 0);
+
 SELECT pgv_free();