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Fix for BUG#4480: In joins with SELECT_STRAIGHT_JOIN re-order tables by outer join dependency,
so we read dependent tables after tables they depend on (this is needed for outer joins)
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@ -853,4 +853,19 @@ id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 const PRIMARY PRIMARY 4 const 1 Using index
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1 SIMPLE t2 ALL NULL NULL NULL NULL 2
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1 SIMPLE t3 ALL NULL NULL NULL NULL 2
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drop table t1,t2;
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create table t1 (a int, b int);
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insert into t1 values (1,1),(2,2),(3,3);
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create table t2 (a int, b int);
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insert into t2 values (1,1), (2,2);
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select * from t2 right join t1 on t2.a=t1.a;
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a b a b
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1 1 1 1
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2 2 2 2
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NULL NULL 3 3
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select straight_join * from t2 right join t1 on t2.a=t1.a;
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a b a b
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1 1 1 1
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2 2 2 2
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NULL NULL 3 3
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DROP TABLE t0,t1,t2,t3;
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@ -606,4 +606,14 @@ INSERT INTO t1 VALUES (0);
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SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=5 WHERE a0=a1 AND a0=1;
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EXPLAIN SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=5 WHERE a0=a1 AND a0=1;
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# Test for BUG#4480
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drop table t1,t2;
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create table t1 (a int, b int);
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insert into t1 values (1,1),(2,2),(3,3);
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create table t2 (a int, b int);
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insert into t2 values (1,1), (2,2);
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select * from t2 right join t1 on t2.a=t1.a;
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select straight_join * from t2 right join t1 on t2.a=t1.a;
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DROP TABLE t0,t1,t2,t3;
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@ -64,6 +64,7 @@ static void best_extension_by_limited_search(JOIN *join,
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uint prune_level);
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static uint determine_search_depth(JOIN* join);
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static int join_tab_cmp(const void* ptr1, const void* ptr2);
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static int join_tab_cmp_straight(const void* ptr1, const void* ptr2);
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/*
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TODO: 'find_best' is here only temporarily until 'greedy_search' is
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tested and approved.
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@ -3678,22 +3679,26 @@ choose_plan(JOIN *join, table_map join_tables)
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{
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uint search_depth= join->thd->variables.optimizer_search_depth;
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uint prune_level= join->thd->variables.optimizer_prune_level;
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bool straight_join= join->select_options & SELECT_STRAIGHT_JOIN;
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DBUG_ENTER("choose_plan");
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if (join->select_options & SELECT_STRAIGHT_JOIN)
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/*
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if (SELECT_STRAIGHT_JOIN option is set)
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reorder tables so dependent tables come after tables they depend
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on, otherwise keep tables in the order they were specified in the query
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else
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Apply heuristic: pre-sort all access plans with respect to the number of
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records accessed.
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*/
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qsort(join->best_ref + join->const_tables, join->tables - join->const_tables,
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sizeof(JOIN_TAB*), straight_join?join_tab_cmp_straight:join_tab_cmp);
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if (straight_join)
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{
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optimize_straight_join(join, join_tables);
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}
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else
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{
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/*
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Heuristic: pre-sort all access plans with respect to the number of
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records accessed.
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*/
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qsort(join->best_ref + join->const_tables, join->tables - join->const_tables,
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sizeof(JOIN_TAB*), join_tab_cmp);
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if (search_depth == MAX_TABLES+2)
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{ /*
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TODO: 'MAX_TABLES+2' denotes the old implementation of find_best before
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@ -3750,6 +3755,23 @@ join_tab_cmp(const void* ptr1, const void* ptr2)
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}
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/*
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Same as join_tab_cmp, but for use with SELECT_STRAIGHT_JOIN.
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*/
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static int
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join_tab_cmp_straight(const void* ptr1, const void* ptr2)
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{
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JOIN_TAB *jt1= *(JOIN_TAB**) ptr1;
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JOIN_TAB *jt2= *(JOIN_TAB**) ptr2;
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if (jt1->dependent & jt2->table->map)
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return 1;
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if (jt2->dependent & jt1->table->map)
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return -1;
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return jt1 > jt2 ? 1 : (jt1 < jt2 ? -1 : 0);
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}
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/*
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Heuristic procedure to automatically guess a reasonable degree of
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exhaustiveness for the greedy search procedure.
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@ -3832,7 +3854,7 @@ optimize_straight_join(JOIN *join, table_map join_tables)
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uint idx= join->const_tables;
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double record_count= 1.0;
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double read_time= 0.0;
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for (JOIN_TAB **pos= join->best_ref + idx ; (s= *pos) ; pos++)
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{
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/* Find the best access method from 's' to the current partial plan */
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