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MDEV-238: SHOW EXPLAIN: Server crashes in JOIN::print_explain with FROM subquery and GROUP BY

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- Support SHOW EXPLAIN for selects that have "Using temporary; Using filesort".
This commit is contained in:
Sergey Petrunya
2012-05-10 13:43:48 +04:00
parent cdc9a1172d
commit 58b9164f04
6 changed files with 106 additions and 12 deletions
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44
sql/sql_select.cc
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@ -7132,28 +7132,36 @@ prev_record_reads(POSITION *positions, uint idx, table_map found_ref)
return found;
}
enum enum_exec_or_opt {WALK_OPTIMIZATION_TABS , WALK_EXECUTION_TABS};
/*
Enumerate join tabs in breadth-first fashion, including const tables.
*/
JOIN_TAB *first_breadth_first_tab(JOIN *join)
JOIN_TAB *first_breadth_first_tab(JOIN *join, enum enum_exec_or_opt tabs_kind)
{
return join->join_tab; /* There's always one (i.e. first) table */
/* There's always one (i.e. first) table */
return (tabs_kind == WALK_EXECUTION_TABS)? join->join_tab:
join->table_access_tabs;
}
JOIN_TAB *next_breadth_first_tab(JOIN *join, JOIN_TAB *tab)
JOIN_TAB *next_breadth_first_tab(JOIN *join, enum enum_exec_or_opt tabs_kind,
JOIN_TAB *tab)
{
JOIN_TAB* const first_top_tab= first_breadth_first_tab(join, tabs_kind);
const uint n_top_tabs_count= (tabs_kind == WALK_EXECUTION_TABS)?
join->top_join_tab_count:
join->top_table_access_tabs_count;
if (!tab->bush_root_tab)
{
/* We're at top level. Get the next top-level tab */
tab++;
if (tab < join->join_tab + join->top_join_tab_count)
if (tab < first_top_tab + n_top_tabs_count)
return tab;
/* No more top-level tabs. Switch to enumerating SJM nest children */
tab= join->join_tab;
tab= first_top_tab;
}
else
{
@ -7177,7 +7185,7 @@ JOIN_TAB *next_breadth_first_tab(JOIN *join, JOIN_TAB *tab)
Ok, "tab" points to a top-level table, and we need to find the next SJM
nest and enter it.
*/
for (; tab < join->join_tab + join->top_join_tab_count; tab++)
for (; tab < first_top_tab + n_top_tabs_count; tab++)
{
if (tab->bush_children)
return tab->bush_children->start;
@ -7201,7 +7209,7 @@ JOIN_TAB *first_top_level_tab(JOIN *join, enum enum_with_const_tables with_const
JOIN_TAB *next_top_level_tab(JOIN *join, JOIN_TAB *tab)
{
tab= next_breadth_first_tab(join, tab);
tab= next_breadth_first_tab(join, WALK_EXECUTION_TABS, tab);
if (tab && tab->bush_root_tab)
tab= NULL;
return tab;
@ -7501,6 +7509,13 @@ get_best_combination(JOIN *join)
join->top_join_tab_count= join->join_tab_ranges.head()->end -
join->join_tab_ranges.head()->start;
/*
Save pointers to select join tabs for SHOW EXPLAIN
*/
join->table_access_tabs= join->join_tab;
join->top_table_access_tabs_count= join->top_join_tab_count;
update_depend_map(join);
DBUG_RETURN(0);
}
@ -7922,6 +7937,7 @@ JOIN::make_simple_join(JOIN *parent, TABLE *temp_table)
!(parent->join_tab_reexec= (JOIN_TAB*) thd->alloc(sizeof(JOIN_TAB))))
DBUG_RETURN(TRUE); /* purecov: inspected */
// psergey-todo: here, save the pointer for original join_tabs.
join_tab= parent->join_tab_reexec;
table= &parent->table_reexec[0]; parent->table_reexec[0]= temp_table;
table_count= top_join_tab_count= 1;
@ -10077,7 +10093,12 @@ void JOIN_TAB::cleanup()
if (cache)
{
cache->free();
cache= 0;
cache= 0; // psergey: this is why we don't see "Using join cache" in SHOW EXPLAIN
// when it is run for "Using temporary+filesort" queries while they
// are at reading-from-tmp-table phase.
//
// TODO ask igor if this can be just moved to later phase
// (JOIN_CACHE objects themselves are not big, arent they)
}
limit= 0;
if (table)
@ -21204,9 +21225,10 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
bool printing_materialize_nest= FALSE;
uint select_id= join->select_lex->select_number;
JOIN_TAB* const first_top_tab= first_breadth_first_tab(join, WALK_OPTIMIZATION_TABS);
for (JOIN_TAB *tab= first_breadth_first_tab(join); tab;
tab= next_breadth_first_tab(join, tab))
for (JOIN_TAB *tab= first_breadth_first_tab(join, WALK_OPTIMIZATION_TABS); tab;
tab= next_breadth_first_tab(join, WALK_OPTIMIZATION_TABS, tab))
{
if (tab->bush_root_tab)
{
@ -21643,7 +21665,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
extra.append(STRING_WITH_LEN("; End temporary"));
else if (tab->do_firstmatch)
{
if (tab->do_firstmatch == join->join_tab - 1)
if (tab->do_firstmatch == /*join->join_tab*/ first_top_tab - 1)
extra.append(STRING_WITH_LEN("; FirstMatch"));
else
{