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This is new code in 9.6, and evidently we missed out testing it as thoroughly as it should have been. Bugs fixed here: 1. Use binary not text mode to open the files on Windows. Before, if the visibility map chanced to contain two bytes that looked like \r\n, Windows' read() would convert that to \n, which both corrupts the map data and causes the file to look shorter than it should. Unless you were *very* unlucky and had an exact multiple of 8K such occurrences in each VM file, this would cause pg_upgrade to report a failure, though with a rather obscure error message. 2. The code for copying rebuilt bytes into the output was simply wrong. It chanced to work okay on little-endian machines but would emit the bytes in the wrong order on big-endian, leading to silent corruption of the visibility map data. 3. The code was careless about alignment of the working buffers. Given all three of an alignment-picky architecture, a compiler that chooses to put the new_vmbuf[] local variable at an odd starting address, and a checksum-enabled database, pg_upgrade would dump core. Point one was reported by Thomas Kellerer, the other two detected by code-reading. Point two is much the nastiest of these issues from an impact standpoint, though fortunately it affects only a minority of users. The Windows issue will definitely bite people, but it seems quite unlikely that there would be undetected corruption from that. In addition, I failed to resist the temptation to do some minor cosmetic adjustments, mostly improving the comments. It would be a good idea to try to improve the error reporting here, but that seems like material for a separate patch. Discussion: <nsjrbh$8li$1@blaine.gmane.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: http://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 http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.