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Since we introduced the idea of leakproof functions, texteq and textne were marked leakproof but their sibling text comparison functions were not. This inconsistency seemed justified because texteq/textne just relied on memcmp() and so could easily be seen to be leakproof, while the other comparison functions are far more complex and indeed can throw input-dependent errors. However, that argument crashed and burned with the addition of nondeterministic collations, because now texteq/textne may invoke the exact same varstr_cmp() infrastructure as the rest. It makes no sense whatever to give them different leakproofness markings. After a certain amount of angst we've concluded that it's all right to consider varstr_cmp() to be leakproof, mostly because the other choice would be disastrous for performance of many queries where leakproofness matters. The input-dependent errors should only be reachable for corrupt input data, or so we hope anyway; certainly, if they are reachable in practice, we've got problems with requirements as basic as maintaining a btree index on a text column. Hence, run around to all the SQL functions that derive from varstr_cmp() and mark them leakproof. This should result in a useful gain in flexibility/performance for queries in which non-leakproofness degrades the efficiency of the query plan. Back-patch to v12 where nondeterministic collations were added. While this isn't an essential bug fix given the determination that varstr_cmp() is leakproof, we might as well apply it now that we've been forced into a post-beta4 catversion bump. Discussion: https://postgr.es/m/31481.1568303470@sss.pgh.pa.us
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/.