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Implemented avg() window function.

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It is based on the sum() function, thus much of the logic is shared.

Considering that there are 2 counters stored within the function, one
that handles the null value, while the other that handles the divisor
for the avg computation, it is possible to remove the counter from the
Item_sum_avg. I have not removed it in this patch as we may choose to
refactor the whole code into a separate class.
This remains to be dicussed.
This commit is contained in:
Vicențiu Ciorbaru
2016-03-16 01:57:59 +02:00
parent aa74fef25e
commit 21651541ce
5 changed files with 156 additions and 0 deletions
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95
mysql-test/r/win_avg.result Normal file
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@ -0,0 +1,95 @@
create table t1 (
pk int primary key,
a int,
b int,
c real
);
insert into t1 values
(101 , 0, 10, 1.1),
(102 , 0, 10, 2.1),
(103 , 1, 10, 3.1),
(104 , 1, 10, 4.1),
(108 , 2, 10, 5.1),
(105 , 2, 20, 6.1),
(106 , 2, 20, 7.1),
(107 , 2, 20, 8.15),
(109 , 4, 20, 9.15),
(110 , 4, 20, 10.15),
(111 , 5, NULL, 11.15),
(112 , 5, 1, 12.25),
(113 , 5, NULL, 13.35),
(114 , 5, NULL, 14.50),
(115 , 5, NULL, 15.65),
(116 , 6, 1, NULL),
(117 , 6, 1, 10),
(118 , 6, 1, 1.1),
(119 , 6, 1, NULL),
(120 , 6, 1, NULL),
(121 , 6, 1, NULL),
(122 , 6, 1, 2.2),
(123 , 6, 1, 20.1),
(124 , 6, 1, -10.4),
(125 , 6, 1, NULL),
(126 , 6, 1, NULL),
(127 , 6, 1, NULL);
select pk, a, b, avg(b) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)
from t1;
pk a b avg(b) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)
101 0 10 10.0000
102 0 10 10.0000
103 1 10 10.0000
104 1 10 10.0000
105 2 20 20.0000
106 2 20 20.0000
107 2 20 16.6667
108 2 10 15.0000
109 4 20 20.0000
110 4 20 20.0000
111 5 NULL 1.0000
112 5 1 1.0000
113 5 NULL 1.0000
114 5 NULL NULL
115 5 NULL NULL
116 6 1 1.0000
117 6 1 1.0000
118 6 1 1.0000
119 6 1 1.0000
120 6 1 1.0000
121 6 1 1.0000
122 6 1 1.0000
123 6 1 1.0000
124 6 1 1.0000
125 6 1 1.0000
126 6 1 1.0000
127 6 1 1.0000
select pk, a, c, avg(c) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)
from t1;
pk a c avg(c) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)
101 0 1.1 1.6
102 0 2.1 1.6
103 1 3.1 3.5999999999999996
104 1 4.1 3.5999999999999996
105 2 6.1 6.6
106 2 7.1 7.116666666666667
107 2 8.15 6.783333333333334
108 2 5.1 6.625000000000001
109 4 9.15 9.65
110 4 10.15 9.65
111 5 11.15 11.7
112 5 12.25 12.25
113 5 13.35 13.366666666666667
114 5 14.5 14.5
115 5 15.65 15.075
116 6 NULL 10
117 6 10 5.55
118 6 1.1 5.55
119 6 NULL 1.0999999999999996
120 6 NULL NULL
121 6 NULL 2.1999999999999997
122 6 2.2 11.15
123 6 20.1 3.966666666666667
124 6 -10.4 4.85
125 6 NULL -10.400000000000002
126 6 NULL NULL
127 6 NULL NULL
drop table t1;

47
mysql-test/t/win_avg.test Normal file
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@ -0,0 +1,47 @@
create table t1 (
pk int primary key,
a int,
b int,
c real
);
insert into t1 values
(101 , 0, 10, 1.1),
(102 , 0, 10, 2.1),
(103 , 1, 10, 3.1),
(104 , 1, 10, 4.1),
(108 , 2, 10, 5.1),
(105 , 2, 20, 6.1),
(106 , 2, 20, 7.1),
(107 , 2, 20, 8.15),
(109 , 4, 20, 9.15),
(110 , 4, 20, 10.15),
(111 , 5, NULL, 11.15),
(112 , 5, 1, 12.25),
(113 , 5, NULL, 13.35),
(114 , 5, NULL, 14.50),
(115 , 5, NULL, 15.65),
(116 , 6, 1, NULL),
(117 , 6, 1, 10),
(118 , 6, 1, 1.1),
(119 , 6, 1, NULL),
(120 , 6, 1, NULL),
(121 , 6, 1, NULL),
(122 , 6, 1, 2.2),
(123 , 6, 1, 20.1),
(124 , 6, 1, -10.4),
(125 , 6, 1, NULL),
(126 , 6, 1, NULL),
(127 , 6, 1, NULL);
--sorted_result
select pk, a, b, avg(b) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)
from t1;
--sorted_result
select pk, a, c, avg(c) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)
from t1;
drop table t1;

10
sql/item_sum.cc
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@ -1681,6 +1681,16 @@ bool Item_sum_avg::add()
return FALSE;
}
void Item_sum_avg::remove()
{
Item_sum_sum::remove();
if (!aggr->arg_is_null(true))
{
DBUG_ASSERT(count > 0);
count--;
}
}
double Item_sum_avg::val_real()
{
DBUG_ASSERT(fixed == 1);

3
sql/item_sum.h
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@ -837,6 +837,8 @@ class Item_sum_count :public Item_sum_int
class Item_sum_avg :public Item_sum_sum
{
public:
// TODO-cvicentiu given that Item_sum_sum now uses a counter of its own, in
// order to implement remove(), it is possible to remove this member.
ulonglong count;
uint prec_increment;
uint f_precision, f_scale, dec_bin_size;
@ -855,6 +857,7 @@ public:
}
void clear();
bool add();
void remove();
double val_real();
// In SPs we might force the "wrong" type with select into a declare variable
longlong val_int() { return val_int_from_real(); }

1
sql/sql_window.cc
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@ -1585,6 +1585,7 @@ bool JOIN::process_window_functions(List<Item> *curr_fields_list)
case Item_sum::COUNT_FUNC:
case Item_sum::SUM_BIT_FUNC:
case Item_sum::SUM_FUNC:
case Item_sum::AVG_FUNC:
{
/*
Frame-aware window function computation. It does one pass, but