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For GENERATED columns, we record all dependencies of the generation expression as AUTO dependencies of the column itself. This means that the generated column is silently dropped if any dependency is removed, even if CASCADE wasn't specified. This is at least a POLA violation, but I think it's actually based on a misreading of the standard. The standard does say that you can't drop a dependent GENERATED column in RESTRICT mode; but that's buried down in a subparagraph, on a different page from some pseudocode that makes it look like an AUTO drop is being suggested. Change this to be more like the way that we handle regular default expressions, ie record the dependencies as NORMAL dependencies of the pg_attrdef entry. Also, make the pg_attrdef entry's dependency on the column itself be INTERNAL not AUTO. That has two effects: * the column will go away, not just lose its default, if any dependency of the expression is dropped with CASCADE. So we don't need any special mechanism to make that happen. * it provides an additional cross-check preventing someone from dropping the default expression without dropping the column. catversion bump because of change in the contents of pg_depend (which also requires a change in one information_schema view). Per bug #17439 from Kevin Humphreys. Although this is a longstanding bug, it seems impractical to back-patch because of the need for catalog contents changes. Discussion: https://postgr.es/m/17439-7df4421197e928f0@postgresql.org
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.