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In the new approach, all files across all tablespaces are sent in a single COPY OUT operation. The CopyData messages are no longer raw archive content; rather, each message is prefixed with a type byte that describes its purpose, e.g. 'n' signifies the start of a new archive and 'd' signifies archive or manifest data. This protocol is significantly more extensible than the old approach, since we can later create more message types, though not without concern for backward compatibility. The new protocol sends a few things to the client that the old one did not. First, it sends the name of each archive explicitly, instead of letting the client compute it. This is intended to make it easier to write future patches that might send archives in a format other that tar (e.g. cpio, pax, tar.gz). Second, it sends explicit progress messages rather than allowing the client to assume that progress is defined by the number of bytes received. This will help with future features where the server compresses the data, or sends it someplace directly rather than transmitting it to the client. The old protocol is still supported for compatibility with previous releases. The new protocol is selected by means of a new TARGET option to the BASE_BACKUP command. Currently, the only supported target is 'client'. Support for additional targets will be added in a later commit. Patch by me. The patch set of which this is a part has had review and/or testing from Jeevan Ladhe, Tushar Ahuja, Suraj Kharage, Dipesh Pandit, and Mark Dilger. Discussion: http://postgr.es/m/CA+TgmoaYZbz0=Yk797aOJwkGJC-LK3iXn+wzzMx7KdwNpZhS5g@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/.