Horizontally, we also have two forces. There’s the force of you pushing on the book from left to right, and again there must be an equal force pushing in the opposite direction. We call that resisting force static friction—“static” because the book’s not budging. This depends on just two things, the specific materials in contact, captured in a coefficient μs, and the normal force (N):
page if you want to
，这一点在新收录的资料中也有详细论述
dmScope: "per-peer"
PostgreSQL 18 changed that. Two new functions: pg_restore_relation_stats and pg_restore_attribute_stats write numbers directly into the catalog tables. Combined with pg_dump --statistics-only, you can treat optimizer statistics as a deployable artifact. Compact, portable, plain SQL.