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MDEV-20265 Unknown column in field list

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This patch corrects the fix of the patch for mdev-19421 that resolved
the problem of parsing some embedded join expressions such as
  t1 join t2 left join t3 on t2.a=t3.a on t1.a=t2.a.
Yet the patch contained a bug that prevented proper context analysis
of the queries where such expressions were used together with comma
separated table references in from clauses.
This commit is contained in:
Igor Babaev
2019-08-15 17:27:49 -07:00
parent ec1f195ecf
commit e746f451d5
3 changed files with 460 additions and 28 deletions
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103
sql/sql_parse.cc
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@ -6435,10 +6435,6 @@ TABLE_LIST *st_select_lex::nest_last_join(THD *thd)
TABLE_LIST *head= join_list->head();
if (head->nested_join && head->nested_join->nest_type & REBALANCED_NEST)
{
List_iterator<TABLE_LIST> li(*join_list);
li++;
while (li++)
li.remove();
DBUG_RETURN(head);
}
@ -6522,13 +6518,13 @@ 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.
@ -6574,9 +6570,9 @@ 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)
@ -6584,15 +6580,15 @@ 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
/ \ / \
@ -6602,15 +6598,58 @@ 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,
@ -6633,7 +6672,11 @@ 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 *r_tbl= right_op_jl->pop();
DBUG_ASSERT(right_op == r_tbl);
TABLE_LIST *l_tbl= right_op_jl->pop();
DBUG_ASSERT(left_op == l_tbl);
TABLE_LIST *cj_nest;
/*
@ -6650,6 +6693,8 @@ 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 ( ; ; )
{
@ -6721,6 +6766,8 @@ 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);
}