The column_statistics  table is not directly accessible by users because it is part of the data dictionary. Histogram information is available using INFORMATION_SCHEMA.COLUMN_STATISTICS , which is implemented as a view on the data dictionary table. COLUMN_STATISTICS  has these columns: 

• SCHEMA_NAME , TABLE_NAME , COLUMN_NAME : The names of the schema, table, and column for which the statistics apply. 

• HISTOGRAM : A JSON  value describing the column statistics, stored as a histogram. 

Column histograms contain buckets for parts of the range of values stored in the column. Histograms are JSON  objects to permit flexibility in the representation of column statistics. Here is a sample histogram object: 

{ "buckets": [ [ 1, 0.3333333333333333 ], [ 2, 0.6666666666666666 ], [ 3, 1 ] ], "null-values": 0, "last-updated": "2017-03-24 13:32:40.000000", "sampling-rate": 1, "histogram-type": "singleton", "number-of-buckets-specified": 128, "data-type": "int", "collation-id": 8 } 

Histogram objects have these keys: 

• buckets : The histogram buckets. Bucket structure depends on the histogram type. 

For singleton  histograms, buckets contain two values: 

•Value 1: The value for the bucket. The type depends on the column data type. 

•Value 2: A double representing the cumulative frequency for the value. For example, .25 and .75 indicate that 25% and 75% of the values in the column are less than or equal to the bucket value. 

For equi-height  histograms, buckets contain four values: 

•Values 1, 2: The lower and upper inclusive values for the bucket. The type depends on the column data type. 

•Value 3: A double representing the cumulative frequency for the value. For example, .25 and .75 indicate that 25% and 75% of the values in the column are less than or equal to the bucket upper value. 

•Value 4: The number of distinct values in the range from the bucket lower value to its upper value. 

• null-values : A number between 0.0 and 1.0 indicating the fraction of column values that are SQL NULL  values. If 0, the column contains no NULL  values. 

