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If the server sends a long stream of data, and the server + network are consistently fast enough to force the recv() loop in pqReadData() to iterate until libpq's input buffer is full, then upon processing the last incomplete message in each bufferload we'd usually double the buffer size, due to supposing that we didn't have enough room in the buffer to finish collecting that message. After filling the newly-enlarged buffer, the cycle repeats, eventually resulting in an out-of-memory situation (which would be reported misleadingly as "lost synchronization with server"). Of course, we should not enlarge the buffer unless we still need room after discarding already-processed messages. This bug dates back quite a long time: pqParseInput3 has had the behavior since perhaps 2003, getCopyDataMessage at least since commit 70066eb1a1ad in 2008. Probably the reason it's not been isolated before is that in common environments the recv() loop would always be faster than the server (if on the same machine) or faster than the network (if not); or at least it wouldn't be slower consistently enough to let the buffer ramp up to a problematic size. The reported cases involve Windows, which perhaps has different timing behavior than other platforms. Per bug #7914 from Shin-ichi Morita, though this is different from his proposed solution. Back-patch to all supported branches.
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/.