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1bc0100d27
Commit 0bf3ae88af allowed direct
foreign table modification; instead of fetching each row, updating
it locally, and then pushing the modification back to the remote
side, we would instead do all the work on the remote server via a
single remote UPDATE or DELETE command. However, that commit only
enabled this optimization when join tree consisted only of the
target table.
This change allows the same optimization when an UPDATE statement
has a FROM clause or a DELETE statement has a USING clause. This
works much like ordinary foreign join pushdown, in that the tables
must be on the same remote server, relevant parts of the query
must be pushdown-safe, and so forth.
Etsuro Fujita, reviewed by Ashutosh Bapat, Rushabh Lathia, and me.
Some formatting corrections by me.
Discussion: http://postgr.es/m/5A57193A.2080003@lab.ntt.co.jp
Discussion: http://postgr.es/m/b9cee735-62f8-6c07-7528-6364ce9347d0@lab.ntt.co.jp
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/.