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MWL#90: Address review feedback part #7

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This commit is contained in:
Sergey Petrunya
2011-03-22 16:46:39 +03:00
parent b9d4c69135
commit 39fe368d68
3 changed files with 83 additions and 43 deletions
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79
sql/sql_select.cc
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@@ -6378,12 +6378,28 @@ JOIN_TAB *first_linear_tab(JOIN *join, bool after_const_tables)
A helper function to loop over all join's join_tab in sequential fashion
DESCRIPTION
Depending on include_bush_roots parameter, JOIN_TABS that represent
SJM-scan/lookups are produced or omitted.
Depending on include_bush_roots parameter, JOIN_TABs that represent
SJM-scan/lookups are either returned or omitted.
SJM-Bush children are returned right after (or in place of) their container
join tab (TODO: does anybody depend on this? A: make_join_readinfo() seems
to.)
to)
For example, if we have this structure:
ot1--ot2--sjm1----------------ot3-...
|
+--it1--it2--it3
calls to next_linear_tab( include_bush_roots=TRUE) will return:
ot1 ot2 sjm1 it1 it2 it3 ot3 ...
while calls to next_linear_tab( include_bush_roots=FALSE) will return:
ot1 ot2 it1 it2 it3 ot3 ...
(note that sjm1 won't be returned).
*/
JOIN_TAB *next_linear_tab(JOIN* join, JOIN_TAB* tab, bool include_bush_roots)
@@ -6418,6 +6434,24 @@ JOIN_TAB *next_linear_tab(JOIN* join, JOIN_TAB* tab, bool include_bush_roots)
}
/*
Start to iterate over all join tables in bush-children-first order, excluding
the const tables (see next_depth_first_tab() comment for details)
*/
JOIN_TAB *first_depth_first_tab(JOIN* join)
{
JOIN_TAB* tab;
/* This means we're starting the enumeration */
if (join->const_tables == join->top_jtrange_tables)
return NULL;
tab= join->join_tab + join->const_tables;
return (tab->bush_children) ? tab->bush_children->start : tab;
}
/*
A helper function to iterate over all join tables in bush-children-first order
@@ -6425,43 +6459,28 @@ JOIN_TAB *next_linear_tab(JOIN* join, JOIN_TAB* tab, bool include_bush_roots)
For example, for this join plan
ot1 ot2 sjm ot3
| +--------+
| |
it1 it2 it3
ot1--ot2--sjm1------------ot3-...
|
|
it1--it2--it3
the function will return
ot1-ot2-it1-it2-it3-sjm-ot3 ...
call to first_depth_first_tab() will return ot1, and subsequent calls to
next_depth_first_tab() will return:
ot2 it1 it2 it3 sjm ot3 ...
*/
JOIN_TAB *next_depth_first_tab(JOIN* join, JOIN_TAB* tab)
{
bool start= FALSE;
if (tab == NULL)
{
/* This means we're starting the enumeration */
if (join->const_tables == join->top_jtrange_tables)
return NULL;
tab= join->join_tab + join->const_tables;
start= TRUE;
}
/* If we're inside SJM nest and have reached its end, get out */
if (tab->last_leaf_in_bush)
return tab->bush_root_tab;
/* Move to next tab in the array we're traversing*/
if (!start)
tab++;
/* Move to next tab in the array we're traversing */
tab++;
//psergey-remove: check:
DBUG_ASSERT(join->join_tab_ranges.head()->end ==
join->join_tab +join->top_jtrange_tables);
if (tab == join->join_tab +join->top_jtrange_tables)
return NULL; /* End */
return NULL; /* Outside SJM nest and reached EOF */
if (tab->bush_children)
return tab->bush_children->start;
@@ -7384,7 +7403,7 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
JOIN_TAB *tab;
table_map current_map;
uint i= join->const_tables;
for (tab= next_depth_first_tab(join, NULL); tab;
for (tab= first_depth_first_tab(join); tab;
tab= next_depth_first_tab(join, tab), i++)
{
bool is_hj;