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Here we adjust the query planner to have it remove items from a window clause's PARTITION BY clause in cases where the pathkey for a column in the PARTITION BY clause is redundant. Doing this allows the optimization added in 9d9c02ccd to stop window aggregation early rather than going into "pass-through" mode to find tuples belonging to the next partition. Also, when we manage to remove all PARTITION BY columns, we now no longer needlessly check that the current tuple belongs to the same partition as the last tuple in nodeWindowAgg.c. If the pathkey was redundant then all tuples must contain the same value for the given redundant column, so there's no point in checking that during execution. Author: David Rowley Reviewed-by: Richard Guo Discussion: https://postgr.es/m/CAApHDvo2ji+hdxrxfXtRtsfSVw3to2o1nCO20qimw0dUGK8hcQ@mail.gmail.com
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/.