51.50. pg_statistic

Normally there is one entry, with stainherit = false, for each table column that has been analyzed. If the table has inheritance children, a second entry with stainherit = true is also created. This row represents the column’s statistics over the inheritance tree, i.e., statistics for the data you’d see with SELECT column FROM table*, whereas the stainherit = false row represents the results of SELECT column FROM ONLY table.

Since different kinds of statistics might be appropriate for different kinds of data, pg_statistic is designed not to assume very much about what sort of statistics it stores. Only extremely general statistics (such as nullness) are given dedicated columns in pg_statistic. Everything else is stored in “slots”, which are groups of associated columns whose content is identified by a code number in one of the slot’s columns. For more information see .

Table 51.50. pg_statistic Columns