Generated Columns

PostgreSQL Virtual Generated Columns Compute Values at Read Time

PostgreSQL 18 can keep a generated column out of the stored row entirely. A virtual generated column evaluates its expression when the column is read, while a stored generated column evaluates on write and occupies storage like an ordinary column. PostgreSQL 18 also makes the virtual form the default when neither VIRTUAL nor STORED is specified. That distinction changes where computation occurs and which expressions PostgreSQL accepts. It also affects triggers, inheritance, partitioning, and logical replication.