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Check ec_relids before bothering to iterate through the EC members. On a perhaps extreme, but still real-world, query in which match_eclasses_to_foreign_key_col() accounts for the bulk of the planner's runtime, this saves nearly 40% of the runtime. It's a bit of a stopgap fix, but it's simple enough to be back-patched to 9.6 where this code came in; so let's do that. David Rowley Discussion: https://postgr.es/m/6970.1545327857@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/.