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Bug #38795: Automatic search depth and nested join's results in server crash

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The greedy optimizer tracks the current level of nested joins and the position
inside these by setting and maintaining a state that's global for the whole FROM
clause.
This state was correctly maintained inside the selection of the next partial plan
table (in best_extension_by_limited_search()). 
greedy_search() also moves the current position by adding the last partial match 
table when there's not enough tables in the partial plan found by 
best_extension_by_limited_search().
This may require update of the global state variables that describe the current
position in the plan if the last table placed by greedy_search is not a top-level 
join table.
Fixed by updating the state after placing the partial plan table in greedy_search()
in the same way this is done on entering the best_extension_by_limited_search().
Fixed the signature of the function called to update the state : 
check_interleaving_with_nj

mysql-test/r/greedy_optimizer.result:
  Bug #38795: test case
mysql-test/t/greedy_optimizer.test:
  Bug #38795: test case
sql/sql_select.cc:
  Bug #38795: correctly update current position when placing
  the next partial plan table in greedy_search().
This commit is contained in:
Georgi Kodinov
2009-01-13 13:09:12 +02:00
parent d501f48757
commit ba47e3bc4d
3 changed files with 168 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
sql/sql_select.cc
View File

@ -100,7 +100,7 @@ static COND* substitute_for_best_equal_field(COND *cond,
void *table_join_idx);
static COND *simplify_joins(JOIN *join, List<TABLE_LIST> *join_list,
COND *conds, bool top);
static bool check_interleaving_with_nj(JOIN_TAB *last, JOIN_TAB *next);
static bool check_interleaving_with_nj(JOIN_TAB *next);
static void restore_prev_nj_state(JOIN_TAB *last);
static void reset_nj_counters(List<TABLE_LIST> *join_list);
static uint build_bitmap_for_nested_joins(List<TABLE_LIST> *join_list,
@ -4705,6 +4705,18 @@ greedy_search(JOIN *join,
*/
join->positions[idx]= best_pos;
/*
Update the interleaving state after extending the current partial plan
with a new table.
We are doing this here because best_extension_by_limited_search reverts
the interleaving state to the one of the non-extended partial plan
on exit.
*/
IF_DBUG(bool is_interleave_error= )
check_interleaving_with_nj (best_table);
/* This has been already checked by best_extension_by_limited_search */
DBUG_ASSERT(!is_interleave_error);
/* find the position of 'best_table' in 'join->best_ref' */
best_idx= idx;
JOIN_TAB *pos= join->best_ref[best_idx];
@ -4722,7 +4734,7 @@ greedy_search(JOIN *join,
--size_remain;
++idx;
DBUG_EXECUTE("opt", print_plan(join, join->tables,
DBUG_EXECUTE("opt", print_plan(join, idx,
record_count, read_time, read_time,
"extended"););
} while (TRUE);
@ -4873,7 +4885,7 @@ best_extension_by_limited_search(JOIN *join,
table_map real_table_bit= s->table->map;
if ((remaining_tables & real_table_bit) &&
!(remaining_tables & s->dependent) &&
(!idx || !check_interleaving_with_nj(join->positions[idx-1].table, s)))
(!idx || !check_interleaving_with_nj(s)))
{
double current_record_count, current_read_time;
@ -5018,7 +5030,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
{
table_map real_table_bit=s->table->map;
if ((rest_tables & real_table_bit) && !(rest_tables & s->dependent) &&
(!idx|| !check_interleaving_with_nj(join->positions[idx-1].table, s)))
(!idx|| !check_interleaving_with_nj(s)))
{
double records, best;
best_access_path(join, s, thd, rest_tables, idx, record_count,
@ -8380,9 +8392,6 @@ static void reset_nj_counters(List<TABLE_LIST> *join_list)
SYNOPSIS
check_interleaving_with_nj()
join Join being processed
last_tab Last table in current partial join order (this function is
not called for empty partial join orders)
next_tab Table we're going to extend the current partial join with
DESCRIPTION
@ -8467,10 +8476,10 @@ static void reset_nj_counters(List<TABLE_LIST> *join_list)
TRUE Requested join order extension not allowed.
*/
static bool check_interleaving_with_nj(JOIN_TAB *last_tab, JOIN_TAB *next_tab)
static bool check_interleaving_with_nj(JOIN_TAB *next_tab)
{
TABLE_LIST *next_emb= next_tab->table->pos_in_table_list->embedding;
JOIN *join= last_tab->join;
JOIN *join= next_tab->join;
if (join->cur_embedding_map & ~next_tab->embedding_map)
{