Such big blocks in query processing should be represented in the debugging trace.

sql/sql_derived.cc

@@ -1129,23 +1129,24 @@ bool mysql_derived_reinit(THD *thd, LEX *lex, TABLE_LIST *derived)
 
 bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived)
 {
+  DBUG_ENTER("pushdown_cond_for_derived");
   if (!cond)
-    return false;
+    DBUG_RETURN(false);
 
   st_select_lex_unit *unit= derived->get_unit();
   st_select_lex *sl= unit->first_select();
 
   /* Do not push conditions into constant derived */
   if (unit->executed)
-    return false;
+    DBUG_RETURN(false);
 
   /* Do not push conditions into recursive with tables */
   if (derived->is_recursive_with_table())
-    return false;
+    DBUG_RETURN(false);
 
   /* Do not push conditions into unit with global ORDER BY ... LIMIT */
   if (unit->fake_select_lex && unit->fake_select_lex->explicit_limit)
-    return false;
+    DBUG_RETURN(false);
 
   /* Check whether any select of 'unit' allows condition pushdown */
   bool some_select_allows_cond_pushdown= false;
@@ -1158,7 +1159,7 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived)
     }
   }
   if (!some_select_allows_cond_pushdown)
-    return false; 
+    DBUG_RETURN(false);
 
   /*
     Build the most restrictive condition extractable from 'cond'
@@ -1173,7 +1174,7 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived)
   if (!extracted_cond)
   {
     /* Nothing can be pushed into the derived table */
-    return false;
+    DBUG_RETURN(false);
   }
   /* Push extracted_cond into every select of the unit specifying 'derived' */
   st_select_lex *save_curr_select= thd->lex->current_select;
@@ -1257,6 +1258,6 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived)
     sl->cond_pushed_into_having= extracted_cond_copy;
   }
   thd->lex->current_select= save_curr_select;
-  return false;
+  DBUG_RETURN(false);
 }