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bpchar equality ignores trailing spaces, so equal values in a column with no length specifier can have different images. Similarly, oidvector equality intentionally pays no attention to the array lower bound field. We nevertheless allowed nbtree deduplication to be used with indexes built with bpchar_ops, bpchar_pattern_ops, or oidvector_ops. A posting list split could therefore place a TID in an index tuple whose key was equal to, but not bytewise identical to, the corresponding table value. This allowed index-only scans to return subtly wrong results. To fix, drop support function 4 from the affected opclasses (we can't change catalog contents on branches 14 through 18, so we just disable deduplication by adding hard-coding to the relevant support functions). Deliberately leave the oidvector opclass alone on branches 14 through 18, though. Disallowing oidvector deduplication on these branches would make pg_amcheck report that pg_proc_proname_args_nsp_index has a corrupt metapage, needlessly alarming users. System catalog oidvector values always have a lower bound of 0, so the issue can't cause harm there; a user can only hit it by indexing an oidvector column that stores the output of a function like trim_array(). It seems very unlikely that any user would ever do that. Users should REINDEX any B-Tree index on a bpchar column. Author: Shihao Zhong <zhong950419@gmail.com> Co-authored-by: Peter Geoghegan <pg@bowt.ie> Reported-by: Ke <kehan5800@gmail.com> Reported-by: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Bug: #19749 Discussion: https://postgr.es/m/19749-d46adf7c7d910b07@postgresql.org Discussion: https://postgr.es/m/CAGRkXqQQ311Lg=62x5UdZtPuRFgpT6XpPMw4X9E3tgbTu162Mw@mail.gmail.com Backpatch-through: 14
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/.