Help Center/ GaussDB/ Developer Guide(Distributed_2.x)/ System Catalogs and System Views/ System Catalogs/ PG_STATISTIC
Updated on 2023-10-23 GMT+08:00
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PG_STATISTIC

PG_STATISTIC records statistics about tables and index columns in a database. By default, only the system administrator can access the system catalog. Common users can access the system catalog only after being authorized.

Table 1 PG_STATISTIC columns

Name

Type

Description

starelid

oid

Table or index that the described column belongs to

starelkind

"char"

Type of an object

staattnum

smallint

Number of the described column in the table, starting from 1

stainherit

boolean

Whether to collect statistics on objects that have inheritance relationship

stanullfrac

real

Percentage of column entries that are null

stawidth

integer

Average stored width, in bytes, of non-null entries

stadistinct

real

Number of distinct, non-null data values in the column for all DNs

  • A value greater than 0 is the actual number of distinct values.
  • A value less than 0 is the negative of a multiplier for the number of rows in the table. (For example, stadistinct=-0.5 indicates that values in a column appear twice on average.)
  • The value 0 indicates that the number of distinct values is unknown.

stakindN

smallint

Code number stating that the type of statistics is stored in slot N of the pg_statistic row

Value range: 1 to 5

staopN

oid

Operator used to generate the statistics stored in slot N. For example, a histogram slot shows the < operator that defines the sort order of the data.

Value range: 1 to 5

stanumbersN

real[]

Numerical statistics of the appropriate type for slot N. The value is NULL if the slot does not involve numerical values.

Value range: 1 to 5

stavaluesN

anyarray

Column data values of the appropriate type for slot N. The value is NULL if the slot type does not store any data values. Each array's element values are actually of the specific column's data type so there is no way to define these columns' type more specifically than anyarray.

Value range: 1 to 5

stadndistinct

real

Number of unique non-null data values in the dn1 column

  • A value greater than 0 is the actual number of distinct values.
  • A value less than 0 is the negative of a multiplier for the number of rows in the table. (For example, stadistinct=-0.5 indicates that values in a column appear twice on average.)
  • The value 0 indicates that the number of distinct values is unknown.

staextinfo

text

Information about extension statistics. This is reserved.

PG_STATISTIC stores sensitive information about statistical objects, such as MCVs. The system administrator and authorized users can access the PG_STATISTIC system catalog to query the sensitive information about the statistical objects.

Parent topic: System Catalogs