[CBRD-24285] Problem of sort limit optimization without checking not …

…null of foreign key (#3509)

http://jira.cubrid.org/browse/CBRD-24285

check not null of fk when sort limit optimization

src/object/class_object.h

@@ -114,6 +114,11 @@ struct pr_type;
 	  (c) == SM_CONSTRAINT_REVERSE_UNIQUE)    \
           ? true : false )
 
+#define SM_IS_CONSTRAINT_NOT_NULL_FAMILY(c) \
+        (((c) == SM_CONSTRAINT_NOT_NULL        || \
+	  (c) == SM_CONSTRAINT_PRIMARY_KEY)	  \
+          ? true : false )
+
 #define SM_IS_CONSTRAINT_INDEX_FAMILY(c) \
         ((SM_IS_CONSTRAINT_UNIQUE_FAMILY(c)    || \
 	 (c) == SM_CONSTRAINT_FOREIGN_KEY      || \

src/optimizer/query_graph.c

@@ -1480,6 +1480,10 @@ static QO_SEGMENT *
 qo_insert_segment (QO_NODE * head, QO_NODE * tail, PT_NODE * node, QO_ENV * env, const char *expr_str)
 {
   QO_SEGMENT *seg = NULL;
+  PT_NODE *entity;
+  MOP cls;
+  SM_CLASS_CONSTRAINT *constraints;
+  SM_ATTRIBUTE *attrp;
 
   QO_ASSERT (env, head != NULL);
   QO_ASSERT (env, env->nsegs < env->Nsegs);
@@ -1522,6 +1526,42 @@ qo_insert_segment (QO_NODE * head, QO_NODE * tail, PT_NODE * node, QO_ENV * env,
 
   bitset_add (&(QO_NODE_SEGS (head)), QO_SEG_IDX (seg));
 
+  /* check is_not_null */
+  entity = QO_NODE_ENTITY_SPEC (head);
+  if (pt_is_name_node (node) && PT_SPEC_IS_ENTITY (entity))
+    {
+      int i;
+      bool found = false;
+      cls = sm_find_class (entity->info.spec.entity_name->info.name.original);
+      constraints = sm_class_constraints (cls);
+
+      while (constraints != NULL)
+	{
+	  if (!SM_IS_CONSTRAINT_NOT_NULL_FAMILY (constraints->type))
+	    {
+	      constraints = constraints->next;
+	      continue;
+	    }
+
+	  /* check columns on this constraint */
+	  for (i = 0; constraints->attributes[i]; i++)
+	    {
+	      attrp = constraints->attributes[i];
+	      if (intl_identifier_casecmp (node->info.name.original, attrp->header.name) == 0)
+		{
+		  QO_SEG_IS_NOT_NULL (seg) = true;
+		  found = true;
+		  break;
+		}
+	    }
+	  if (found)
+	    {
+	      break;
+	    }
+	  constraints = constraints->next;
+	}
+    }
+
   env->nsegs++;
 
   return seg;
@@ -8305,6 +8345,7 @@ qo_seg_clear (QO_ENV * env, int idx)
   QO_SEG_SHARED_ATTR (seg) = false;
   QO_SEG_IDX (seg) = idx;
   QO_SEG_FUNC_INDEX (seg) = false;
+  QO_SEG_IS_NOT_NULL (seg) = false;
   bitset_init (&(QO_SEG_INDEX_TERMS (seg)), env);
 }
 
@@ -9600,6 +9641,12 @@ qo_is_pk_fk_full_join (QO_ENV * env, QO_NODE * fk_node, QO_NODE * pk_node)
 	  fk_seg = QO_TERM_INDEX_SEG (term, 1);
 	}
 
+      /* fk must have the NOT_NULL constraint */
+      if (!QO_SEG_IS_NOT_NULL (fk_seg))
+	{
+	  return false;
+	}
+
       /* make sure pk_seg and fk_seg reference the same position in the two indexes */
       for (j = 0; j < pk_idx->nsegs; j++)
 	{

src/optimizer/query_graph.h

@@ -503,6 +503,7 @@ struct qo_segment
   /* The index of this segment in the corresponding Env's seg array. */
   int idx;
   bool is_function_index;
+  bool is_not_null;
 };
 
 #define QO_SEG_ENV(seg)			(seg)->env
@@ -522,6 +523,7 @@ struct qo_segment
 #define QO_SEG_IS_OID_SEG(seg)		(QO_NODE_OID_SEG(QO_SEG_HEAD(seg)) == seg)
 #define QO_SEG_INDEX_TERMS(seg)         (seg)->index_terms
 #define QO_SEG_FUNC_INDEX(seg)		(seg)->is_function_index
+#define QO_SEG_IS_NOT_NULL(seg)		(seg)->is_not_null
 #define OID_SEG_NAME                    "OID$"
 
 struct qo_eqclass