Statistics target
Also called: default_statistics_target, SET STATISTICS
The statistics target is a knob that controls how detailed a column's statistics are, how many most-common values and histogram buckets ANALYZE keeps, and how many rows it samples. The default is 100.
What this means
A dial for how detailed a column's statistics are, how many common values and histogram buckets ANALYZE keeps, and how big a sample it takes. The default is 100. Turn it up on a column the planner keeps misjudging and it gets a finer, more accurate picture, at the cost of a slower ANALYZE.
Why it matters operationally
Raising it (globally with default_statistics_target, or per column with ALTER TABLE ... SET STATISTICS) gives the planner a sharper picture of skewed data, at the cost of slower ANALYZE and slightly slower planning. It is the main lever when a column's estimates are too coarse.