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Bug #21302: Result not properly sorted when using an ORDER BY on a second

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table in a join
 The optimizer removes redundant columns in ORDER BY. It is considering 
redundant every reference to const table column, e.g b in :
create table t1 (a int, b int, primary key(a)); 
select 1 from t1 order by b where a = 1

But it must not remove references to const table columns if the 
const table is an outer table because there still can be 2 values :
the const value and NULL. e.g.:
create table t1 (a int, b int, primary key(a));
select t2.b c from t1 left join t1 t2 on (t1.a = t2.a and t2.a = 5) 
  order by c;


mysql-test/r/join_outer.result:
  Bug #21302: Result not properly sorted when using an ORDER BY on a second 
              table in a join
   - don't remove columns of const tables in ORDER BY if the const table 
     is an outer table.
mysql-test/r/order_by.result:
  Bug #21302: Result not properly sorted when using an ORDER BY on a second 
              table in a join
   - test case
mysql-test/t/order_by.test:
  Bug #21302: Result not properly sorted when using an ORDER BY on a second 
              table in a join
   - test case
sql/sql_select.cc:
  Bug #21302: Result not properly sorted when using an ORDER BY on a second 
              table in a join
   - don't remove columns of const tables in ORDER BY if the const table 
     is an outer table.
This commit is contained in:
unknown
2006-08-14 15:45:48 +03:00
parent 1cf65f311d
commit 06a302eff2
4 changed files with 72 additions and 2 deletions
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3
sql/sql_select.cc
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@ -5976,7 +5976,8 @@ eq_ref_table(JOIN *join, ORDER *start_order, JOIN_TAB *tab)
if (tab->cached_eq_ref_table) // If cached
return tab->eq_ref_table;
tab->cached_eq_ref_table=1;
if (tab->type == JT_CONST) // We can skip const tables
/* We can skip const tables only if not an outer table */
if (tab->type == JT_CONST && !tab->first_inner)
return (tab->eq_ref_table=1); /* purecov: inspected */
if (tab->type != JT_EQ_REF || tab->table->maybe_null)
return (tab->eq_ref_table=0); // We must use this