MDEV-4402 A function to visualize histograms data.

mysql-test/r/statistics.result

@@ -1416,6 +1416,65 @@ WORLD_INNODB	CITY	Country	1	17.5819
 WORLD_INNODB	COUNTRYLANGUAGE	PRIMARY	1	4.2232
 WORLD_INNODB	COUNTRYLANGUAGE	PRIMARY	2	1.0000
 WORLD_INNODB	COUNTRYLANGUAGE	Percentage	1	2.7640
+set use_stat_tables='preferably';
+set histogram_size=100;
+set histogram_type='SINGLE_PREC_HB';
+ANALYZE TABLE CountryLanguage;
+set histogram_size=255;
+set histogram_type='DOUBLE_PREC_HB';
+ANALYZE TABLE City;
+select db_name,table_name,column_name,min_value,max_value,nulls_ratio,avg_length,avg_frequency,hist_size,hist_type,hex(histogram),decode_histogram(histogram,hist_type) from mysql.column_stats where table_name='CountryLanguage' and column_name = 'Percentage';;
+db_name	world
+table_name	CountryLanguage
+column_name	Percentage
+min_value	0.0
+max_value	99.9
+nulls_ratio	0.0000
+avg_length	4.0000
+avg_frequency	2.7640
+hist_size	0
+hist_type	NULL
+hex(histogram)	NULL
+decode_histogram(histogram,hist_type)	NULL
+db_name	world_innodb
+table_name	CountryLanguage
+column_name	Percentage
+min_value	0.0
+max_value	99.9
+nulls_ratio	0.0000
+avg_length	4.0000
+avg_frequency	2.7640
+hist_size	100
+hist_type	SINGLE_PREC_HB
+hex(histogram)	0000000000000000000000000101010101010101010202020303030304040404050505050606070707080809090A0A0B0C0D0D0E0E0F10111213131415161718191B1C1E202224292A2E33373B4850575F6A76818C9AA7B9C4CFDADFE5EBF0F4F8FAFCFF
+decode_histogram(histogram,hist_type)	0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.004,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.000,0.004,0.000,0.000,0.004,0.000,0.000,0.000,0.004,0.000,0.000,0.000,0.004,0.000,0.000,0.000,0.004,0.000,0.004,0.000,0.000,0.004,0.000,0.004,0.000,0.004,0.000,0.004,0.004,0.004,0.000,0.004,0.000,0.004,0.004,0.004,0.004,0.004,0.000,0.004,0.004,0.004,0.004,0.004,0.004,0.008,0.004,0.008,0.008,0.008,0.008,0.020,0.004,0.016,0.020,0.016,0.016,0.051,0.031,0.027,0.031,0.043,0.047,0.043,0.043,0.055,0.051,0.071,0.043,0.043,0.043,0.020,0.024,0.024,0.020,0.016,0.016,0.008,0.008,0.012
+select db_name,table_name,column_name,min_value,max_value,nulls_ratio,avg_length,avg_frequency,hist_size,hist_type,hex(histogram),decode_histogram(histogram,hist_type) from mysql.column_stats where table_name='City' and column_name = 'Population';;
+db_name	world
+table_name	City
+column_name	Population
+min_value	42
+max_value	10500000
+nulls_ratio	0.0000
+avg_length	4.0000
+avg_frequency	1.0467
+hist_size	0
+hist_type	NULL
+hex(histogram)	NULL
+decode_histogram(histogram,hist_type)	NULL
+db_name	world_innodb
+table_name	City
+column_name	Population
+min_value	42
+max_value	10500000
+nulls_ratio	0.0000
+avg_length	4.0000
+avg_frequency	1.0467
+hist_size	255
+hist_type	DOUBLE_PREC_HB
+hex(histogram)	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
+decode_histogram(histogram,hist_type)	0.00047,0.00198,0.00601,0.00008,0.00008,0.00005,0.00011,0.00006,0.00009,0.00008,0.00006,0.00009,0.00008,0.00009,0.00008,0.00009,0.00006,0.00006,0.00008,0.00008,0.00008,0.00011,0.00009,0.00008,0.00009,0.00006,0.00011,0.00006,0.00012,0.00012,0.00012,0.00012,0.00011,0.00011,0.00014,0.00011,0.00011,0.00011,0.00014,0.00006,0.00011,0.00009,0.00011,0.00009,0.00015,0.00015,0.00015,0.00009,0.00018,0.00015,0.00015,0.00015,0.00017,0.00018,0.00018,0.00015,0.00018,0.00020,0.00024,0.00021,0.00023,0.00027,0.00024,0.00024,0.00027,0.00023,0.00020,0.00029,0.00020,0.00027,0.00020,0.00027,0.00026,0.00034,0.00024,0.00034,0.00031,0.00037,0.00043,0.00038,0.00038,0.00035,0.00047,0.00056,0.00058,0.00041,0.00047,0.00056,0.00072,0.00044,0.00060,0.00072,0.00061,0.00072,0.00066,0.00085,0.00075,0.00078,0.00082,0.00073,0.00108,0.00089,0.00105,0.00105,0.00151,0.00150,0.00110,0.00145,0.00163,0.00160,0.00165,0.00232,0.00201,0.00371,0.00365,0.00383,0.00459,0.00583,0.00662,0.00984,0.00969,0.01080,0.01379,0.02063,0.04308,0.05960,0.15816
+set histogram_type=default;
+set histogram_size=default;
 use test;
 DROP DATABASE world;
 SELECT UPPER(db_name), UPPER(table_name), cardinality

mysql-test/t/statistics.test

@@ -564,6 +564,22 @@ SELECT UPPER(db_name), UPPER(table_name),
        index_name, prefix_arity, avg_frequency
   FROM mysql.index_stats;
 
+set use_stat_tables='preferably';
+--disable_result_log
+set histogram_size=100;
+set histogram_type='SINGLE_PREC_HB';
+ANALYZE TABLE CountryLanguage;
+set histogram_size=255;
+set histogram_type='DOUBLE_PREC_HB';
+ANALYZE TABLE City;
+--enable_result_log
+
+--query_vertical select db_name,table_name,column_name,min_value,max_value,nulls_ratio,avg_length,avg_frequency,hist_size,hist_type,hex(histogram),decode_histogram(histogram,hist_type) from mysql.column_stats where table_name='CountryLanguage' and column_name = 'Percentage';
+--query_vertical select db_name,table_name,column_name,min_value,max_value,nulls_ratio,avg_length,avg_frequency,hist_size,hist_type,hex(histogram),decode_histogram(histogram,hist_type) from mysql.column_stats where table_name='City' and column_name = 'Population';
+
+set histogram_type=default;
+set histogram_size=default;
+
 use test;
 
 DROP DATABASE world;

sql/item_create.cc

@@ -614,6 +614,19 @@ protected:
 };
 
 
+class Create_func_decode_histogram : public Create_func_arg2
+{
+public:
+  Item *create_2_arg(THD *thd, Item *arg1, Item *arg2);
+
+  static Create_func_decode_histogram s_singleton;
+
+protected:
+  Create_func_decode_histogram() {}
+  virtual ~Create_func_decode_histogram() {}
+};
+
+
 class Create_func_concat_ws : public Create_native_func
 {
 public:
@@ -3231,6 +3244,13 @@ Create_func_concat::create_native(THD *thd, LEX_STRING name,
   return new (thd->mem_root) Item_func_concat(*item_list);
 }
 
+Create_func_decode_histogram Create_func_decode_histogram::s_singleton;
+
+Item *
+Create_func_decode_histogram::create_2_arg(THD *thd, Item *arg1, Item *arg2)
+{
+  return new (thd->mem_root) Item_func_decode_histogram(arg1, arg2);
+}
 
 Create_func_concat_ws Create_func_concat_ws::s_singleton;
 
@@ -5377,6 +5397,7 @@ static Native_func_registry func_array[] =
   { { C_STRING_WITH_LEN("DAYOFYEAR") }, BUILDER(Create_func_dayofyear)},
   { { C_STRING_WITH_LEN("DECODE") }, BUILDER(Create_func_decode)},
   { { C_STRING_WITH_LEN("DEGREES") }, BUILDER(Create_func_degrees)},
+  { { C_STRING_WITH_LEN("DECODE_HISTOGRAM") }, BUILDER(Create_func_decode_histogram)},
   { { C_STRING_WITH_LEN("DES_DECRYPT") }, BUILDER(Create_func_des_decrypt)},
   { { C_STRING_WITH_LEN("DES_ENCRYPT") }, BUILDER(Create_func_des_encrypt)},
   { { C_STRING_WITH_LEN("DIMENSION") }, GEOM_BUILDER(Create_func_dimension)},

sql/item_strfunc.cc

@@ -60,6 +60,7 @@ C_MODE_START
 C_MODE_END
 #include "sql_show.h"                           // append_identifier
 #include <sql_repl.h>
+#include "sql_statistics.h"
 
 /**
    @todo Remove this. It is not safe to use a shared String object.
@@ -472,6 +473,82 @@ void Item_func_aes_decrypt::fix_length_and_dec()
    set_persist_maybe_null(1);
 }
 
+///////////////////////////////////////////////////////////////////////////////
+
+
+const char *histogram_types[] =
+           {"SINGLE_PREC_HB", "DOUBLE_PREC_HB", 0};
+static TYPELIB hystorgam_types_typelib=
+  { array_elements(histogram_types),
+    "histogram_types",
+    histogram_types, NULL};
+const char *representation_by_type[]= {"%.3f", "%.5f"};
+
+String *Item_func_decode_histogram::val_str(String *str)
+{
+  DBUG_ASSERT(fixed == 1);
+  char buff[STRING_BUFFER_USUAL_SIZE];
+  String *res, tmp(buff, sizeof(buff), &my_charset_bin);
+  int type;
+
+  tmp.length(0);
+  if (!(res= args[1]->val_str(&tmp)) ||
+      (type= find_type(res->c_ptr_safe(),
+                       &hystorgam_types_typelib, MYF(0))) <= 0)
+  {
+    null_value= 1;
+    return 0;
+  }
+  type--;
+
+  tmp.length(0);
+  if (!(res= args[0]->val_str(&tmp)))
+  {
+    null_value= 1;
+    return 0;
+  }
+  if (type == DOUBLE_PREC_HB && res->length() % 2 != 0)
+    res->length(res->length() - 1); // one byte is unused
+
+  double prev= 0.0;
+  uint i;
+  str->length(0);
+  bool first= true;
+  const uchar *p= (uchar*)res->c_ptr();
+  for (i= 0; i < res->length(); i++)
+  {
+    char numbuf[32];
+    double val;
+    switch (type)
+    {
+    case SINGLE_PREC_HB:
+      val= p[i] / ((double)((1 << 8) - 1));
+      break;
+    case DOUBLE_PREC_HB:
+      val= ((uint16 *)(p + i))[0] / ((double)((1 << 16) - 1));
+      i++;
+      break;
+    default:
+      val= 0;
+      DBUG_ASSERT(0);
+    }
+    /* show delta with previous value */
+    int size= my_snprintf(numbuf, sizeof(numbuf),
+                          representation_by_type[type], val - prev);
+    if (first)
+      first= false;
+    else
+      str->append(",");
+    str->append(numbuf, size);
+    prev= val;
+  }
+
+  null_value=0;
+  return str;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
 
 /**
   Concatenate args with the following premises:

sql/item_strfunc.h

@@ -143,6 +143,22 @@ public:
   const char *func_name() const { return "concat"; }
 };
 
+class Item_func_decode_histogram :public Item_str_func
+{
+  String tmp_value;
+public:
+  Item_func_decode_histogram(Item *a, Item *b)
+    :Item_str_func(a, b) {}
+  String *val_str(String *);
+  void fix_length_and_dec()
+  {
+    collation.set(system_charset_info);
+    max_length= MAX_BLOB_WIDTH;
+    set_persist_maybe_null(1);
+  }
+  const char *func_name() const { return "decode_histogram"; }
+};
+
 class Item_func_concat_ws :public Item_str_func
 {
   String tmp_value;

sql/sys_vars.cc

@@ -3970,8 +3970,7 @@ static Sys_var_ulong Sys_histogram_size(
        SESSION_VAR(histogram_size), CMD_LINE(REQUIRED_ARG),
        VALID_RANGE(0, 255), DEFAULT(0), BLOCK_SIZE(1));
 
-const char *histogram_types[] =
+extern const char *histogram_types[];
-           {"SINGLE_PREC_HB", "DOUBLE_PREC_HB", 0};
 static Sys_var_enum Sys_histogram_type(
        "histogram_type",
        "Specifies type of the histograms created by ANALYZE. "