From b9d4c69135f8f11135793e22e554c3a9f6517983 Mon Sep 17 00:00:00 2001
From: Sergey Petrunya <psergey@askmonty.org>
Date: Tue, 22 Mar 2011 13:17:14 +0300
Subject: [PATCH] MWL#90: Address review feedback part #6: more clearer code in
next_linear_tab() function
---
sql/sql_select.cc | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index b5d6cc1acb..33690deffa 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -6389,21 +6389,31 @@ JOIN_TAB *first_linear_tab(JOIN *join, bool after_const_tables)
JOIN_TAB *next_linear_tab(JOIN* join, JOIN_TAB* tab, bool include_bush_roots)
{
if (include_bush_roots && tab->bush_children)
+ {
+ /* This JOIN_TAB is a SJM nest; Start from first table in nest */
return tab->bush_children->start;
+ }
DBUG_ASSERT(!tab->last_leaf_in_bush || tab->bush_root_tab);
- if (tab->last_leaf_in_bush)
- tab= tab->bush_root_tab;
- if (tab->bush_root_tab)
- return ++tab;
+ if (tab->bush_root_tab) /* Are we inside an SJM nest */
+ {
+ /* Inside SJM nest */
+ if (!tab->last_leaf_in_bush)
+ return tab+1; /* Return next in nest */
+ /* Continue from the sjm on the top level */
+ tab= tab->bush_root_tab;
+ }
+ /* If no more JOIN_TAB's on the top level */
if (++tab == join->join_tab + join->top_jtrange_tables)
return NULL;
if (!include_bush_roots && tab->bush_children)
+ {
+ /* This JOIN_TAB is a SJM nest; Start from first table in nest */
tab= tab->bush_children->start;
-
+ }
return tab;
}
--
2.30.9