## # 52.50. `pg_statistic_ext`

The catalog `pg_statistic_ext`

holds definitions of extended planner statistics. Each row in this catalog corresponds to a *statistics object* created with `CREATE STATISTICS`

.

**Table 52.50. pg_statistic_ext Columns**

Column Type Description |
---|

`oid` `oid` Row identifier |

`stxrelid` `oid` (references `pg_class` .`oid` )Table containing the columns described by this object |

`stxname` `name` Name of the statistics object |

`stxnamespace` `oid` (references `pg_namespace` .`oid` )The OID of the namespace that contains this statistics object |

`stxowner` `oid` (references `pg_authid` .`oid` )Owner of the statistics object |

`stxstattarget` `int4` `stxstattarget` controls the level of detail of statistics accumulated for this statistics object by `ANALYZE` . A zero value indicates that no statistics should be collected. A negative value says to use the maximum of the statistics targets of the referenced columns, if set, or the system default statistics target. Positive values of `stxstattarget` determine the target number of “most common values” to collect. |

`stxkeys` `int2vector` (references `pg_attribute` .`attnum` )An array of attribute numbers, indicating which table columns are covered by this statistics object; for example a value of `1 3` would mean that the first and the third table columns are covered |

`stxkind` `char[]` An array containing codes for the enabled statistics kinds; valid values are: `d` for n-distinct statistics, `f` for functional dependency statistics, `m` for most common values (MCV) list statistics, and `e` for expression statistics |

`stxexprs` `pg_node_tree` Expression trees (in `nodeToString()` representation) for statistics object attributes that are not simple column references. This is a list with one element per expression. Null if all statistics object attributes are simple references. |

The `pg_statistic_ext`

entry is filled in completely during `CREATE STATISTICS`

, but the actual statistical values are not computed then. Subsequent `ANALYZE`

commands compute the desired values and populate an entry in the `pg_statistic_ext_data`

catalog.