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| author | Alexander Barkov <bar@mariadb.com> | 2019-03-28 10:28:52 +0400 |
|---|---|---|
| committer | Alexander Barkov <bar@mariadb.com> | 2019-03-28 14:12:31 +0400 |
| commit | a5ac029f8a96aae19f09b99a821cae5ddf8c0751 (patch) | |
| tree | 984f0f862cd508fcf9858636be9fc7638be3fadd /sql/item_sum.h | |
| parent | 3e1f3d3e2f14a157121b92bd4b76e986f1846454 (diff) | |
| download | mariadb-git-a5ac029f8a96aae19f09b99a821cae5ddf8c0751.tar.gz | |
MDEV-19062 Item_sum_variance: move recurrence_m, recurrence_s, count to a separate class
Diffstat (limited to 'sql/item_sum.h')
| -rw-r--r-- | sql/item_sum.h | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/sql/item_sum.h b/sql/item_sum.h index 3600f625f3f..abe6192fcd1 100644 --- a/sql/item_sum.h +++ b/sql/item_sum.h @@ -964,18 +964,38 @@ But, this falls prey to catastrophic cancellation. Instead, use the recurrence */ +class Stddev +{ + double m_m; + double m_s; + ulonglong m_count; +public: + Stddev() :m_m(0), m_s(0), m_count(0) { } + Stddev(double nr) :m_m(nr), m_s(0.0), m_count(1) { } + Stddev(const uchar *); + void to_binary(uchar *) const; + void recurrence_next(double nr); + double result(bool is_simple_variance); + ulonglong count() const { return m_count; } + static uint32 binary_size() + { + return (uint32) (sizeof(double) * 2 + sizeof(ulonglong)); + }; +}; + + + class Item_sum_variance : public Item_sum_num { + Stddev m_stddev; bool fix_length_and_dec(); public: - double recurrence_m, recurrence_s; /* Used in recurrence relation. */ - ulonglong count; uint sample; uint prec_increment; Item_sum_variance(THD *thd, Item *item_par, uint sample_arg): - Item_sum_num(thd, item_par), count(0), + Item_sum_num(thd, item_par), sample(sample_arg) {} Item_sum_variance(THD *thd, Item_sum_variance *item); @@ -997,7 +1017,7 @@ public: const Type_handler *type_handler() const { return &type_handler_double; } void cleanup() { - count= 0; + m_stddev= Stddev(); Item_sum_num::cleanup(); } Item *get_copy(THD *thd) |