database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-29 05:21:33 +03:00
Code Activity

Fix for BUG#4480: In joins with SELECT_STRAIGHT_JOIN re-order tables by outer join dependency,

Browse Source 
so we read dependent tables after tables they depend on (this is needed for outer joins)
This commit is contained in:
sergefp@mysql.com
2004-12-21 01:59:58 +03:00
parent e0484ec64b
commit e89f5a7136
3 changed files with 57 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

42
sql/sql_select.cc
View File

@ -64,6 +64,7 @@ static void best_extension_by_limited_search(JOIN *join,
uint prune_level);
static uint determine_search_depth(JOIN* join);
static int join_tab_cmp(const void* ptr1, const void* ptr2);
static int join_tab_cmp_straight(const void* ptr1, const void* ptr2);
/*
TODO: 'find_best' is here only temporarily until 'greedy_search' is
tested and approved.
@ -3678,22 +3679,26 @@ choose_plan(JOIN *join, table_map join_tables)
{
uint search_depth= join->thd->variables.optimizer_search_depth;
uint prune_level= join->thd->variables.optimizer_prune_level;
bool straight_join= join->select_options & SELECT_STRAIGHT_JOIN;
DBUG_ENTER("choose_plan");
if (join->select_options & SELECT_STRAIGHT_JOIN)
/*
if (SELECT_STRAIGHT_JOIN option is set)
reorder tables so dependent tables come after tables they depend
on, otherwise keep tables in the order they were specified in the query
else
Apply heuristic: pre-sort all access plans with respect to the number of
records accessed.
*/
qsort(join->best_ref + join->const_tables, join->tables - join->const_tables,
sizeof(JOIN_TAB*), straight_join?join_tab_cmp_straight:join_tab_cmp);
if (straight_join)
{
optimize_straight_join(join, join_tables);
}
else
{
/*
Heuristic: pre-sort all access plans with respect to the number of
records accessed.
*/
qsort(join->best_ref + join->const_tables, join->tables - join->const_tables,
sizeof(JOIN_TAB*), join_tab_cmp);
if (search_depth == MAX_TABLES+2)
{ /*
TODO: 'MAX_TABLES+2' denotes the old implementation of find_best before
@ -3750,6 +3755,23 @@ join_tab_cmp(const void* ptr1, const void* ptr2)
}
/*
Same as join_tab_cmp, but for use with SELECT_STRAIGHT_JOIN.
*/
static int
join_tab_cmp_straight(const void* ptr1, const void* ptr2)
{
JOIN_TAB *jt1= *(JOIN_TAB**) ptr1;
JOIN_TAB *jt2= *(JOIN_TAB**) ptr2;
if (jt1->dependent & jt2->table->map)
return 1;
if (jt2->dependent & jt1->table->map)
return -1;
return jt1 > jt2 ? 1 : (jt1 < jt2 ? -1 : 0);
}
/*
Heuristic procedure to automatically guess a reasonable degree of
exhaustiveness for the greedy search procedure.
@ -3832,7 +3854,7 @@ optimize_straight_join(JOIN *join, table_map join_tables)
uint idx= join->const_tables;
double record_count= 1.0;
double read_time= 0.0;
for (JOIN_TAB **pos= join->best_ref + idx ; (s= *pos) ; pos++)
{
/* Find the best access method from 's' to the current partial plan */