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Fixed LP bug #729039.

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If join condition is of the form <t2.key>=<t1.no_key> then the server
performs no index look-ups when looking for matching rows of t2 for
the rows from t1 with t1.no_key=NULL. It happens because the function
add_not_null_conds() injects an additional condition of the form 
IS NOT NULL(<t1.no_key>) into the WHERE condition.
However if the join condition was of the form <t.key>=<outer_ref> no
additional null rejecting predicate was generated. This could lead
to extra records in the result set if the value of <outer_ref> happened
to be NULL.
The new code injects null rejecting predicates of the form 
IS NOT NULL(<outer_ref>) and evaluates them before the first row
the subquery is constructed.
This commit is contained in:
Igor Babaev
2011-03-07 22:09:21 -08:00
parent 0d5d68f684
commit 3d3d5f1d43
7 changed files with 158 additions and 4 deletions
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2
sql/sql_select.h
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@ -798,6 +798,7 @@ public:
ORDER *order, *group_list, *proc_param; //hold parameters of mysql_select
COND *conds; // ---"---
Item *conds_history; // store WHERE for explain
COND *outer_ref_cond; ///<part of conds containing only outer references
TABLE_LIST *tables_list; ///<hold 'tables' parameter of mysql_select
List<TABLE_LIST> *join_list; ///< list of joined tables in reverse order
COND_EQUAL *cond_equal;
@ -903,6 +904,7 @@ public:
no_const_tables= FALSE;
first_select= sub_select;
outer_ref_cond= 0;
}
int prepare(Item ***rref_pointer_array, TABLE_LIST *tables, uint wind_num,