As a reflection of the two distinct versions just mentioned, the upgrade occurs in two steps: Step 1: Data dictionary upgrade. This step upgrades: The data dictionary tables in the schema. If the actual data dictionary version is lower than the current expected version, the server creates data dictionary tables with updated definitions, copies persisted metadata to the new tables, atomically replaces the old tables with the new ones, and reinitializes the data dictionary. mysql The Performance Schema, , and . INFORMATION_SCHEMAndbinfo