diff options
Diffstat (limited to 'sql/sql_parse.cc')
| -rw-r--r-- | sql/sql_parse.cc | 102 |
1 files changed, 74 insertions, 28 deletions
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc index 813f3fb3d57..9b1cb836867 100644 --- a/sql/sql_parse.cc +++ b/sql/sql_parse.cc @@ -3629,6 +3629,7 @@ mysql_execute_command(THD *thd) case GET_NO_ARG: case GET_DISABLED: DBUG_ASSERT(0); + /* fall through */ case 0: case GET_FLAGSET: case GET_ENUM: @@ -8350,9 +8351,9 @@ TABLE_LIST *st_select_lex::nest_last_join(THD *thd) DBUG_ENTER("nest_last_join"); TABLE_LIST *head= join_list->head(); - if (head->nested_join && head->nested_join->nest_type & REBALANCED_NEST) + if (head->nested_join && (head->nested_join->nest_type & REBALANCED_NEST)) { - join_list->empty(); + head= join_list->pop(); DBUG_RETURN(head); } @@ -8436,13 +8437,13 @@ void st_select_lex::add_joined_table(TABLE_LIST *table) context and right-associative in another context. In this query - SELECT * FROM t1 JOIN t2 LEFT JOIN t3 ON t2.a=t3.a (Q1) + SELECT * FROM t1 JOIN t2 LEFT JOIN t3 ON t2.a=t3.a (Q1) JOIN is left-associative and the query Q1 is interpreted as - SELECT * FROM (t1 JOIN t2) LEFT JOIN t3 ON t2.a=t3.a. + SELECT * FROM (t1 JOIN t2) LEFT JOIN t3 ON t2.a=t3.a. While in this query - SELECT * FROM t1 JOIN t2 LEFT JOIN t3 ON t2.a=t3.a ON t1.b=t2.b (Q2) + SELECT * FROM t1 JOIN t2 LEFT JOIN t3 ON t2.a=t3.a ON t1.b=t2.b (Q2) JOIN is right-associative and the query Q2 is interpreted as - SELECT * FROM t1 JOIN (t2 LEFT JOIN t3 ON t2.a=t3.a) ON t1.b=t2.b + SELECT * FROM t1 JOIN (t2 LEFT JOIN t3 ON t2.a=t3.a) ON t1.b=t2.b JOIN is right-associative if it is used with ON clause or with USING clause. Otherwise it is left-associative. @@ -8488,9 +8489,9 @@ void st_select_lex::add_joined_table(TABLE_LIST *table) J LJ - ON / \ / \ - t1 LJ - ON (TQ3*) => J t2 - / \ / \ - t3 t2 t1 t3 + t1 LJ - ON (TQ3*) => t3 J + / \ / \ + t3 t2 t1 t2 With several left associative JOINs SELECT * FROM t1 JOIN t2 JOIN t3 LEFT JOIN t4 ON t3.a=t4.a (Q4) @@ -8498,15 +8499,15 @@ void st_select_lex::add_joined_table(TABLE_LIST *table) J1 LJ - ON / \ / \ - t1 LJ - ON J2 t4 + t1 J2 J2 t4 / \ => / \ - J2 t4 J1 t3 - / \ / \ - t2 t3 t1 t2 + t2 LJ - ON J1 t3 + / \ / \ + t3 t4 t1 t2 - Here's another example: - SELECT * - FROM t1 JOIN t2 LEFT JOIN t3 JOIN t4 ON t3.a=t4.a ON t2.b=t3.b (Q5) + Here's another example: + SELECT * + FROM t1 JOIN t2 LEFT JOIN t3 JOIN t4 ON t3.a=t4.a ON t2.b=t3.b (Q5) J LJ - ON / \ / \ @@ -8516,15 +8517,58 @@ void st_select_lex::add_joined_table(TABLE_LIST *table) / \ t3 t4 - If the transformed nested join node node is a natural join node like in - the following query - SELECT * FROM t1 JOIN t2 LEFT JOIN t3 USING(a) (Q6) - the transformation additionally has to take care about setting proper - references in the field natural_join for both operands of the natural - join operation. - The function also has to change the name resolution context for ON - expressions used in the transformed join expression to take into - account the tables of the left_op node. + If the transformed nested join node node is a natural join node like in + the following query + SELECT * FROM t1 JOIN t2 LEFT JOIN t3 USING(a) (Q6) + the transformation additionally has to take care about setting proper + references in the field natural_join for both operands of the natural + join operation. + + The queries that combine comma syntax for join operation with + JOIN expression require a special care. Consider the query + SELECT * FROM t1, t2 JOIN t3 LEFT JOIN t4 ON t3.a=t4.a (Q7) + This query is equivalent to the query + SELECT * FROM (t1, t2) JOIN t3 LEFT JOIN t4 ON t3.a=t4.a + The latter is transformed in the same way as query Q1 + + J LJ - ON + / \ / \ + (t1,t2) LJ - ON => J t4 + / \ / \ + t3 t4 (t1,t2) t3 + + A transformation similar to the transformation for Q3 is done for + the following query with RIGHT JOIN + SELECT * FROM t1, t2 JOIN t3 RIGHT JOIN t4 ON t3.a=t4.a (Q8) + + J LJ - ON + / \ / \ + t3 LJ - ON => t4 J + / \ / \ + t4 (t1,t2) (t1,t2) t3 + + The function also has to change the name resolution context for ON + expressions used in the transformed join expression to take into + account the tables of the left_op node. + + TODO: + A more elegant solution would be to implement the transformation that + eliminates nests for cross join operations. For Q7 it would work like this: + + J LJ - ON + / \ / \ + (t1,t2) LJ - ON => (t1,t2,t3) t4 + / \ + t3 t4 + + For Q8 with RIGHT JOIN the transformation would work similarly: + + J LJ - ON + / \ / \ + t3 LJ - ON => t4 (t1,t2,t3) + / \ + t4 (t1,t2) + */ bool st_select_lex::add_cross_joined_table(TABLE_LIST *left_op, @@ -8549,11 +8593,9 @@ bool st_select_lex::add_cross_joined_table(TABLE_LIST *left_op, } TABLE_LIST *tbl; - List<TABLE_LIST> *jl= &right_op->nested_join->join_list; + List<TABLE_LIST> *right_op_jl= right_op->join_list; TABLE_LIST *cj_nest; - add_joined_table(right_op); - /* Create the node NJ for a new nested join for the future inclusion of left_op in it. Initially the nest is empty. @@ -8568,6 +8610,8 @@ bool st_select_lex::add_cross_joined_table(TABLE_LIST *left_op, List<TABLE_LIST> *cjl= &cj_nest->nested_join->join_list; cjl->empty(); + List<TABLE_LIST> *jl= &right_op->nested_join->join_list; + DBUG_ASSERT(jl->elements == 2); /* Look for the left most node tbl of the right_op tree */ for ( ; ; ) { @@ -8640,6 +8684,8 @@ bool st_select_lex::add_cross_joined_table(TABLE_LIST *left_op, create a new top level nested join node. */ right_op->nested_join->nest_type|= REBALANCED_NEST; + if (unlikely(right_op_jl->push_front(right_op))) + DBUG_RETURN(true); DBUG_RETURN(false); } |