[CBRD-24502] backport- The problem of updating statistical informatio…

…n when performing DDL (#4412)

http://jira.cubrid.org/browse/CBRD-24502

It is modified so that statistics are not updated during DDL. DDL includes index creation and drop, such as 'CREATE INDEX'. The optimizer sets the default selectivity for new statistics that are not updated.

src/object/schema_manager.c

@@ -3915,6 +3915,76 @@ sm_update_statistics (MOP classop, bool with_fullscan)
   return error;
 }
 
+/*
+ * sm_update_statistics_without_gathering_stats () - fetch the statistics and
+ *    						     cache them with the class.
+ *   return: NO_ERROR on success, non-zero for ERROR
+ *   classop(in): class object
+ *   with_fullscan(in): true iff WITH FULLSCAN
+ *
+ * NOTE: We will delay updating statistics until a transaction is committed
+ *       when it is requested during other processing, such as
+ *       "alter table ...." or "create index ...".
+ */
+int
+sm_update_statistics_without_gathering_stats (MOP classop, bool with_fullscan)
+{
+  int error = NO_ERROR, is_class = 0;
+  SM_CLASS *class_;
+
+  assert_release (classop != NULL);
+
+  /* only try to get statistics if we know the class has been flushed if it has a temporary oid, it isn't flushed and
+   * there are no statistics */
+
+  if (classop != NULL && !OID_ISTEMP (WS_OID (classop)))
+    {
+      is_class = locator_is_class (classop, DB_FETCH_QUERY_READ);
+      if (is_class < 0)
+	{
+	  return is_class;
+	}
+    }
+  if (is_class > 0)
+    {
+
+      /* make sure the workspace is flushed before calculating stats */
+      if (locator_flush_all_instances (classop, DONT_DECACHE) != NO_ERROR)
+	{
+	  assert (er_errid () != NO_ERROR);
+	  return er_errid ();
+	}
+
+      if (classop->object != NULL)
+	{			/* check cache */
+	  /* why are we checking authorization here ? */
+	  error = au_fetch_class_force (classop, &class_, AU_FETCH_READ);
+	  if (error == NO_ERROR)
+	    {
+	      if (class_->stats != NULL)
+		{
+		  stats_free_statistics (class_->stats);
+		  class_->stats = NULL;
+		}
+
+	      /* make sure the class is flushed before acquiring stats, see comments above in
+	       * sm_get_class_with_statistics */
+	      if (locator_flush_class (classop) != NO_ERROR)
+		{
+		  assert (er_errid () != NO_ERROR);
+		  return (er_errid ());
+		}
+
+	      /* get the new ones, should do this at the same time as the update operation to avoid two server
+	       * calls */
+	      error = stats_get_statistics (WS_OID (classop), 0, &class_->stats);
+	    }
+	}
+    }
+
+  return error;
+}
+
 /*
  * sm_update_all_statistics() - Update the statistics for all classes
  * 			        in the database.
@@ -12430,7 +12500,7 @@ update_subclasses (DB_OBJLIST * subclasses)
 		    }
 		  else if (!class_->dont_decache_constraints_or_flush && class_->class_type == SM_CLASS_CT)
 		    {
-		      error = sm_update_statistics (sub->op, STATS_WITH_SAMPLING);
+		      error = sm_update_statistics_without_gathering_stats (sub->op, STATS_WITH_SAMPLING);
 		    }
 
 		  classobj_free_template (class_->new_);
@@ -12772,7 +12842,7 @@ update_class (SM_TEMPLATE * template_, MOP * classmop, int auto_res, DB_AUTH aut
   /* All objects are updated, now we can update class statistics also. */
   if (template_->class_type == SM_CLASS_CT)
     {
-      error = sm_update_statistics (template_->op, STATS_WITH_SAMPLING);
+      error = sm_update_statistics_without_gathering_stats (template_->op, STATS_WITH_SAMPLING);
       if (error != NO_ERROR)
 	{
 	  goto error_return;
@@ -13926,7 +13996,7 @@ sm_drop_index (MOP classop, const char *constraint_name)
 	  goto severe_error;
 	}
 
-      if (sm_update_statistics (classop, STATS_WITH_SAMPLING) != NO_ERROR)
+      if (sm_update_statistics_without_gathering_stats (classop, STATS_WITH_SAMPLING) != NO_ERROR)
 	{
 	  goto severe_error;
 	}
@@ -14760,7 +14830,7 @@ sm_add_constraint (MOP classop, DB_CONSTRAINT_TYPE constraint_type, const char *
 	      goto error_exit;
 	    }
 
-	  error = sm_update_statistics (newmop, STATS_WITH_SAMPLING);
+	  error = sm_update_statistics_without_gathering_stats (newmop, STATS_WITH_SAMPLING);
 	  if (error != NO_ERROR)
 	    {
 	      goto error_exit;