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Sergey Petrunya 2011-07-12 13:02:19 +04:00
commit 419c20f10a
7 changed files with 236 additions and 73 deletions
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115
mysql-test/r/negation_elimination.result
View file

@ -375,6 +375,121 @@ a
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# XOR (Note: XOR is negated by negating one of the operands)
# Should return 6,7
SELECT * FROM t1 WHERE ((a > 5) XOR (a > 7));
a
6
7
# Should return 0..5,8..19
SELECT * FROM t1 WHERE ((NOT (a > 5)) XOR (a > 7));
a
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SELECT * FROM t1 WHERE ((a > 5) XOR (NOT (a > 7)));
a
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SELECT * FROM t1 WHERE NOT ((a > 5) XOR (a > 7));
a
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# Should return 6,7
SELECT * FROM t1 WHERE NOT ((NOT (a > 5)) XOR (a > 7));
a
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SELECT * FROM t1 WHERE NOT ((a > 5) XOR (NOT (a > 7)));
a
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# Should return 0..5,8..19
SELECT * FROM t1 WHERE NOT ((NOT (a > 5)) XOR (NOT (a > 7)));
a
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# Should have empty result
SELECT * FROM t1 WHERE (NULL XOR (a > 7));
a
SELECT * FROM t1 WHERE NOT (NULL XOR (a > 7));
a
# Should be simplified to "...WHERE (a XOR a)
EXPLAIN EXTENDED SELECT * FROM t1 WHERE NOT ((NOT a) XOR (a));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 index NULL a 5 NULL 21 100.00 Using where; Using index
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` xor `test`.`t1`.`a`)
# Should be simplified to "...WHERE (a XOR a)
EXPLAIN EXTENDED SELECT * FROM t1 WHERE NOT (a XOR (NOT a));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 index NULL a 5 NULL 21 100.00 Using where; Using index
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` xor `test`.`t1`.`a`)
# End XOR
delete from t1 where a > 3;
select a, not(not(a)) from t1;
a not(not(a))

29
mysql-test/t/negation_elimination.test
View file

@ -65,6 +65,35 @@ select * from t1 where not((a < 5 and a < 10) and (not(a > 16) or a > 17));
explain select * from t1 where ((a between 5 and 15) and (not(a like 10)));
select * from t1 where ((a between 5 and 15) and (not(a like 10)));
--echo # XOR (Note: XOR is negated by negating one of the operands)
--echo # Should return 6,7
SELECT * FROM t1 WHERE ((a > 5) XOR (a > 7));
--echo # Should return 0..5,8..19
SELECT * FROM t1 WHERE ((NOT (a > 5)) XOR (a > 7));
SELECT * FROM t1 WHERE ((a > 5) XOR (NOT (a > 7)));
SELECT * FROM t1 WHERE NOT ((a > 5) XOR (a > 7));
--echo # Should return 6,7
SELECT * FROM t1 WHERE NOT ((NOT (a > 5)) XOR (a > 7));
SELECT * FROM t1 WHERE NOT ((a > 5) XOR (NOT (a > 7)));
--echo # Should return 0..5,8..19
SELECT * FROM t1 WHERE NOT ((NOT (a > 5)) XOR (NOT (a > 7)));
--echo # Should have empty result
SELECT * FROM t1 WHERE (NULL XOR (a > 7));
SELECT * FROM t1 WHERE NOT (NULL XOR (a > 7));
--echo # Should be simplified to "...WHERE (a XOR a)
EXPLAIN EXTENDED SELECT * FROM t1 WHERE NOT ((NOT a) XOR (a));
--echo # Should be simplified to "...WHERE (a XOR a)
EXPLAIN EXTENDED SELECT * FROM t1 WHERE NOT (a XOR (NOT a));
--echo # End XOR
delete from t1 where a > 3;
select a, not(not(a)) from t1;
explain extended select a, not(not(a)), not(a <= 2 and not(a)), not(a not like "1"), not (a not in (1,2)), not(a != 2) from t1 where not(not(a)) having not(not(a));

45
sql/item_cmpfunc.cc
View file

@ -5065,23 +5065,21 @@ bool Item_func_like::turboBM_matches(const char* text, int text_len) const
very fast to use.
*/
longlong Item_cond_xor::val_int()
longlong Item_func_xor::val_int()
{
DBUG_ASSERT(fixed == 1);
List_iterator<Item> li(list);
Item *item;
int result=0;
null_value=0;
while ((item=li++))
int result= 0;
null_value= false;
for (uint i= 0; i < arg_count; i++)
{
result^= (item->val_int() != 0);
if (item->null_value)
result^= (args[i]->val_int() != 0);
if (args[i]->null_value)
{
null_value=1;
null_value= true;
return 0;
}
}
return (longlong) result;
return result;
}
/**
@ -5122,6 +5120,33 @@ Item *Item_bool_rowready_func2::neg_transformer(THD *thd)
return item;
}
/**
XOR can be negated by negating one of the operands:
NOT (a XOR b) => (NOT a) XOR b
=> a XOR (NOT b)
@param thd Thread handle
@return New negated item
*/
Item *Item_func_xor::neg_transformer(THD *thd)
{
Item *neg_operand;
Item_func_xor *new_item;
if ((neg_operand= args[0]->neg_transformer(thd)))
// args[0] has neg_tranformer
new_item= new(thd->mem_root) Item_func_xor(neg_operand, args[1]);
else if ((neg_operand= args[1]->neg_transformer(thd)))
// args[1] has neg_tranformer
new_item= new(thd->mem_root) Item_func_xor(args[0], neg_operand);
else
{
neg_operand= new(thd->mem_root) Item_func_not(args[0]);
new_item= new(thd->mem_root) Item_func_xor(neg_operand, args[1]);
}
return new_item;
}
/**
a IS NULL -> a IS NOT NULL.

55
sql/item_cmpfunc.h
View file

@ -391,6 +391,22 @@ public:
}
};
/**
XOR inherits from Item_bool_func2 because it is not optimized yet.
Later, when XOR is optimized, it needs to inherit from
Item_cond instead. See WL#5800.
*/
class Item_func_xor :public Item_bool_func2
{
public:
Item_func_xor(Item *i1, Item *i2) :Item_bool_func2(i1, i2) {}
enum Functype functype() const { return XOR_FUNC; }
const char *func_name() const { return "xor"; }
longlong val_int();
void top_level_item() {}
Item *neg_transformer(THD *thd);
};
class Item_func_not :public Item_bool_func
{
public:
@ -1817,45 +1833,6 @@ inline bool is_cond_or(Item *item)
return (cond_item->functype() == Item_func::COND_OR_FUNC);
}
/*
XOR is Item_cond, not an Item_int_func because we could like to
optimize (a XOR b) later on. It's low prio, though
*/
class Item_cond_xor :public Item_cond
{
public:
Item_cond_xor(Item *i1,Item *i2) :Item_cond(i1,i2)
{
/*
Items must be stored in args[] as well because this Item_cond is
treated as a FUNC_ITEM (see type()). I.e., users of it will get
it's children by calling arguments(), not argument_list(). This
is a temporary solution until XOR is optimized and treated like
a full Item_cond citizen.
*/
arg_count= 2;
args= tmp_arg;
args[0]= i1;
args[1]= i2;
}
enum Functype functype() const { return COND_XOR_FUNC; }
/* TODO: remove the next line when implementing XOR optimization */
enum Type type() const { return FUNC_ITEM; }
longlong val_int();
const char *func_name() const { return "xor"; }
void top_level_item() {}
/* Since child Items are stored in args[], Items cannot be added.
However, since Item_cond_xor is treated as a FUNC_ITEM (see
type()), the methods below should never be called.
*/
bool add(Item *item) { DBUG_ASSERT(FALSE); return FALSE; }
bool add_at_head(Item *item) { DBUG_ASSERT(FALSE); return FALSE; }
bool add_at_head(List<Item> *nlist) { DBUG_ASSERT(FALSE); return FALSE; }
void copy_andor_arguments(THD *thd, Item_cond *item) { DBUG_ASSERT(FALSE); }
};
/* Some useful inline functions */
inline Item *and_conds(Item *a, Item *b)

2
sql/item_func.h
View file

@ -44,7 +44,7 @@ public:
enum Functype { UNKNOWN_FUNC,EQ_FUNC,EQUAL_FUNC,NE_FUNC,LT_FUNC,LE_FUNC,
GE_FUNC,GT_FUNC,FT_FUNC,
LIKE_FUNC,ISNULL_FUNC,ISNOTNULL_FUNC,
COND_AND_FUNC, COND_OR_FUNC, COND_XOR_FUNC,
COND_AND_FUNC, COND_OR_FUNC, XOR_FUNC,
BETWEEN, IN_FUNC, MULT_EQUAL_FUNC,
INTERVAL_FUNC, ISNOTNULLTEST_FUNC,
SP_EQUALS_FUNC, SP_DISJOINT_FUNC,SP_INTERSECTS_FUNC,

59
sql/opt_subselect.cc
View file

@ -183,7 +183,7 @@ static bool convert_subq_to_sj(JOIN *parent_join, Item_in_subselect *subq_pred);
static bool convert_subq_to_jtbm(JOIN *parent_join,
Item_in_subselect *subq_pred, bool *remove);
static TABLE_LIST *alloc_join_nest(THD *thd);
static uint get_tmp_table_rec_length(List<Item> &items);
static uint get_tmp_table_rec_length(Item **p_list, uint elements);
static double get_tmp_table_lookup_cost(THD *thd, double row_count,
uint row_size);
static double get_tmp_table_write_cost(THD *thd, double row_count,
@ -1806,8 +1806,11 @@ bool optimize_semijoin_nests(JOIN *join, table_map all_table_map)
sjm->materialization_cost.convert_from_cost(subjoin_read_time);
sjm->rows= subjoin_out_rows;
List<Item> &right_expr_list=
sj_nest->sj_subq_pred->unit->first_select()->item_list;
// Don't use the following list because it has "stale" items. use
// ref_pointer_array instead:
//
//List<Item> &right_expr_list=
// sj_nest->sj_subq_pred->unit->first_select()->item_list;
/*
Adjust output cardinality estimates. If the subquery has form
@ -1825,17 +1828,20 @@ bool optimize_semijoin_nests(JOIN *join, table_map all_table_map)
See also get_post_group_estimate().
*/
SELECT_LEX *subq_select= sj_nest->sj_subq_pred->unit->first_select();
{
for (uint i=0 ; i < join->const_tables + sjm->tables ; i++)
{
JOIN_TAB *tab= join->best_positions[i].table;
join->map2table[tab->table->tablenr]= tab;
}
List_iterator<Item> it(right_expr_list);
Item *item;
//List_iterator<Item> it(right_expr_list);
Item **ref_array= subq_select->ref_pointer_array;
Item **ref_array_end= ref_array + subq_select->item_list.elements;
table_map map= 0;
while ((item= it++))
map |= item->used_tables();
//while ((item= it++))
for (;ref_array < ref_array_end; ref_array++)
map |= (*ref_array)->used_tables();
map= map & ~PSEUDO_TABLE_BITS;
Table_map_iterator tm_it(map);
int tableno;
@ -1850,7 +1856,8 @@ bool optimize_semijoin_nests(JOIN *join, table_map all_table_map)
/*
Calculate temporary table parameters and usage costs
*/
uint rowlen= get_tmp_table_rec_length(right_expr_list);
uint rowlen= get_tmp_table_rec_length(subq_select->ref_pointer_array,
subq_select->item_list.elements);
double lookup_cost= get_tmp_table_lookup_cost(join->thd,
subjoin_out_rows, rowlen);
double write_cost= get_tmp_table_write_cost(join->thd,
@ -1897,13 +1904,15 @@ bool optimize_semijoin_nests(JOIN *join, table_map all_table_map)
Length of the temptable record, in bytes
*/
static uint get_tmp_table_rec_length(List<Item> &items)
static uint get_tmp_table_rec_length(Item **p_items, uint elements)
{
uint len= 0;
Item *item;
List_iterator<Item> it(items);
while ((item= it++))
//List_iterator<Item> it(items);
Item **p_item;
for (p_item= p_items; p_item < p_items + elements ; p_item++)
{
item = *p_item;
switch (item->result_type()) {
case REAL_RESULT:
len += sizeof(double);
@ -2908,19 +2917,23 @@ bool setup_sj_materialization_part1(JOIN_TAB *sjm_tab)
SJ_MATERIALIZATION_INFO *sjm= emb_sj_nest->sj_mat_info;
THD *thd= tab->join->thd;
/* First the calls come to the materialization function */
List<Item> &item_list= emb_sj_nest->sj_subq_pred->unit->first_select()->item_list;
//List<Item> &item_list= emb_sj_nest->sj_subq_pred->unit->first_select()->item_list;
DBUG_ASSERT(sjm->is_used);
/*
Set up the table to write to, do as select_union::create_result_table does
*/
sjm->sjm_table_param.init();
sjm->sjm_table_param.field_count= item_list.elements;
sjm->sjm_table_param.bit_fields_as_long= TRUE;
List_iterator<Item> it(item_list);
Item *right_expr;
while((right_expr= it++))
sjm->sjm_table_cols.push_back(right_expr);
//List_iterator<Item> it(item_list);
SELECT_LEX *subq_select= emb_sj_nest->sj_subq_pred->unit->first_select();
Item **p_item= subq_select->ref_pointer_array;
Item **p_end= p_item + subq_select->item_list.elements;
//while((right_expr= it++))
for(;p_item != p_end; p_item++)
sjm->sjm_table_cols.push_back(*p_item);
sjm->sjm_table_param.field_count= subq_select->item_list.elements;
if (!(sjm->table= create_tmp_table(thd, &sjm->sjm_table_param,
sjm->sjm_table_cols, (ORDER*) 0,
@ -2952,8 +2965,8 @@ bool setup_sj_materialization_part2(JOIN_TAB *sjm_tab)
SJ_MATERIALIZATION_INFO *sjm= emb_sj_nest->sj_mat_info;
THD *thd= tab->join->thd;
uint i;
List<Item> &item_list= emb_sj_nest->sj_subq_pred->unit->first_select()->item_list;
List_iterator<Item> it(item_list);
//List<Item> &item_list= emb_sj_nest->sj_subq_pred->unit->first_select()->item_list;
//List_iterator<Item> it(item_list);
if (!sjm->is_sj_scan)
{
@ -3069,11 +3082,13 @@ bool setup_sj_materialization_part2(JOIN_TAB *sjm_tab)
*/
sjm->copy_field= new Copy_field[sjm->sjm_table_cols.elements];
//it.rewind();
Item **p_item= emb_sj_nest->sj_subq_pred->unit->first_select()->ref_pointer_array;
for (uint i=0; i < sjm->sjm_table_cols.elements; i++)
{
bool dummy;
Item_equal *item_eq;
Item *item= (it++)->real_item();
//Item *item= (it++)->real_item();
Item *item= (*(p_item++))->real_item();
DBUG_ASSERT(item->type() == Item::FIELD_ITEM);
Field *copy_to= ((Item_field*)item)->field;
/*
@ -4513,7 +4528,9 @@ bool JOIN::choose_subquery_plan(table_map join_tables)
C. Compute execution costs.
*/
/* C.1 Compute the cost of the materialization strategy. */
uint rowlen= get_tmp_table_rec_length(unit->first_select()->item_list);
//uint rowlen= get_tmp_table_rec_length(unit->first_select()->item_list);
uint rowlen= get_tmp_table_rec_length(ref_pointer_array,
select_lex->item_list.elements);
/* The cost of writing one row into the temporary table. */
double write_cost= get_tmp_table_write_cost(thd, inner_record_count_1,
rowlen);

2
sql/sql_yacc.yy
View file

@ -7172,7 +7172,7 @@ expr:
| expr XOR expr %prec XOR
{
/* XOR is a proprietary extension */
$$ = new (YYTHD->mem_root) Item_cond_xor($1, $3);
$$ = new (YYTHD->mem_root) Item_func_xor($1, $3);
if ($$ == NULL)
MYSQL_YYABORT;
}