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MDEV-4840: Wrong result (missing rows) on LEFT JOIN with InnoDB tables

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Fix two problems in table elimination code:
- Before marking a "value" as bound, check if it is already bound. Marking the 
  same value as bound twice could confuse a module that depends on this value, 
  because Dep_module_XXX use counters to know when they become bound.

- When checking whether field is part of a key, ignore "extended keys" property.
This commit is contained in:
Sergey Petrunya 2013-08-22 14:12:10 +04:00
commit 37e9714c5e
3 changed files with 43 additions and 3 deletions
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20
mysql-test/r/table_elim.result
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@ -628,4 +628,24 @@ id select_type table type possible_keys key key_len ref rows filtered Extra
Warnings:
Note 1003 select `test`.`t2`.`b` AS `b` from `test`.`t2` where <expr_cache><`test`.`t2`.`b`>(<in_optimizer>(`test`.`t2`.`b`,<exists>(select sum(1) from dual having (<cache>(`test`.`t2`.`b`) = <ref_null_helper>(sum(1))))))
DROP TABLE t1,t2;
#
# MDEV-4840: Wrong result (missing rows) on LEFT JOIN with InnoDB tables
#
CREATE TABLE t1 (alpha3 VARCHAR(3));
INSERT INTO t1 VALUES ('USA'),('CAN');
CREATE TABLE t2 ( t3_code VARCHAR(3), name VARCHAR(64));
INSERT INTO t2 VALUES ('USA','Austin'),('USA','Boston');
CREATE TABLE t3 ( code VARCHAR(3), name VARCHAR(64), PRIMARY KEY (code), UNIQUE KEY (name));
INSERT INTO t3 VALUES ('CAN','Canada'),('USA','United States');
SELECT * FROM t1 LEFT JOIN ( t2 LEFT JOIN t3 ON t2.t3_code = t3.code ) ON t1.alpha3 = t3.code;
alpha3 t3_code name code name
USA USA Austin USA United States
USA USA Boston USA United States
CAN NULL NULL NULL NULL
SELECT t1.alpha3 FROM t1 LEFT JOIN ( t2 LEFT JOIN t3 ON t2.t3_code = t3.code ) ON t1.alpha3 = t3.code;
alpha3
USA
USA
CAN
DROP TABLE t1, t2, t3;
SET optimizer_switch=@save_optimizer_switch;