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The grammar of this command run on indexes with column names has always been authorized by the parser, and it has never been documented. Since 911e702, it is possible to define opclass parameters as of CREATE INDEX, which actually broke the old case of ALTER INDEX/TABLE where relation-level parameters n_distinct and n_distinct_inherited could be defined for an index (see 76a47c0 and its thread where this point has been touched, still remained unused). Attempting to do that in v13~ would cause the index to become unusable, as there is a new dedicated code path to load opclass parameters instead of the relation-level ones previously available. Note that it is possible to fix things with a manual catalog update to bring the relation back online. This commit disables this command for now as the use of column names for indexes does not make sense anyway, particularly when it comes to index expressions where names are automatically computed. One way to properly support this case properly in the future would be to use column numbers when it comes to indexes, in the same way as ALTER INDEX .. ALTER COLUMN .. SET STATISTICS. Partitioned indexes were already blocked, but not indexes. Some tests are added for both cases. There was some code in ANALYZE to enforce n_distinct to be used for an index expression if the parameter was defined, but just remove it for now until/if there is support for this (note that index-level parameters never had support in pg_dump either, previously), so this was just dead code. Reported-by: Matthijs van der Vleuten Author: Nathan Bossart, Michael Paquier Reviewed-by: Vik Fearing, Dilip Kumar Discussion: https://postgr.es/m/17220-15d684c6c2171a83@postgresql.org Backpatch-through: 13
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/.