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The planner simplifies boolean comparisons such as "x = true" and "x = false" down to "x" and "NOT x" respectively, to have a canonical form to ease comparisons. However, if we want to use an index on x, the index AM APIs require us to reconstitute the comparison-operator form of the indexqual. While that works, in bitmap indexscans the canonical form of the qual was emitted as a "filter" condition although it really only needs to be a "recheck" condition, because create_bitmap_scan_plan didn't recognize the equivalence of that form with the generated indexqual. booleq() is pretty cheap so that likely doesn't make very much difference, but it's unsightly so let's clean it up. To fix, add a case to predicate_implied_by() to recognize the equivalence of such clauses. This is a relatively low-cost place to add a check, and perhaps it will have additional use cases in future. Richard Guo and Tom Lane, per discussion of bug #17618 from Sindy Senorita. Discussion: https://postgr.es/m/17618-7a2240bfaa7e84ae@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/.