PG_EXT_STATS

PG_EXT_STATS displays extended statistics stored in PG_STATISTIC_EXT. The extension statistics means multiple columns of statistics. For details about the columns, see Table 1.

**Table 1** PG_EXT_STATS columns
Name	Type	Reference	Description
schemaname	name	PG_NAMESPACE.nspname	Name of the schema that contains a table.
tablename	name	relname in PG_CLASS	Table name
attname	int2vector	PG_STATISTIC_EXT.stakey	Columns to be combined for collecting statistics
inherited	boolean	-	Inherited tables are not supported currently. The value of this column is false.
null_frac	real	-	Percentage of column combinations that are null to all records
avg_width	integer	-	Average width of column combinations, in byte
n_distinct	real	-	Estimated number of distinct values in a column combination if the value is greater than 0 Negative number obtained by multiplying the result calculated by dividing the number of distinct values by the number of rows by –1 if the value is less than 0. For example, –1 indicates that the number of distinct values is the same as the number of rows for a column combination. The negated form is used when ANALYZE believes that the number of distinct values is likely to increase as the table grows. The positive form is used when the column seems to have a fixed number of possible values. The number of distinct values is unknown if the value is 0.
n_dndistinct	real	-	Number of not-null distinct values in the dn1 column combination. Exact number of distinct values if the value is greater than 0. Negative number obtained by multiplying the result calculated by dividing the number of distinct values by the number of rows by –1 if the value is less than 0. For example, if a value in a column combination appears twice in average, n_dndistinct equals –0.5. The number of distinct values is unknown if the value is 0.
most_common_vals	anyarray	-	List of the most common values in a column combination. If this combination does not have the most common values, this column will be NULL. None of the most common values in the column is NULL.
most_common_freqs	real[]	-	List of the frequencies of the most common values in a column combination. The frequencies are obtained by dividing the number of occurrences of each value by the number of rows. If the value of most_common_vals is NULL, the value of this column is NULL.
most_common_vals_null	anyarray	-	List of the most common values in a column combination. If this combination does not have the most common values, this column will be NULL. At least one of the common values in the column is NULL.
most_common_freqs_null	real[]	-	List of the frequencies of the most common values in a column combination. The frequencies are obtained by dividing the number of occurrences of each value by the number of rows. If the value of most_common_vals_null is NULL, the value of this column is NULL.
histogram_bounds	anyarray	-	Boundary value list of the histogram
partitionname	name	PG_PARTITION.relname	Name of the level-1 partition in the partitioned table. For a non-partitioned table, this field is left blank.
subpartitionname	name	PG_PARTITION.relname	Name of the level-2 partition in the partitioned table. For a distributed system, this field is left blank.