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After the recovery target timeline is changed, we would still recycle and preallocate WAL segments on the old target timeline. Those WAL segments created for the old timeline are a waste of space, although otherwise harmless. The problem is that when installing a recycled WAL segment as a future one, ThisTimeLineID is used to construct the filename. ThisTimeLineID is initialized in the checkpointer process to the recovery target timeline at startup, but it was not updated when the startup process chooses a new target timeline (recovery_target_timeline='latest'). To fix, always update ThisTimeLineID before recycling WAL segments at a restartpoint. This still leaves a small window where we might install WAL segments under wrong timeline ID, if the target timeline is changed just as we're about to start recycling. Also, when we're not on the target timeline yet, but still replaying some older timeline, we'll install WAL segments to the newer timeline anyway and they will still go wasted. We'll just live with the waste in that situation. Commit to 9.2 and 9.1. Older versions didn't change recovery target timeline after startup, and for master, I'll commit a slightly different variant of this.
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. Changes between all PostgreSQL releases are recorded in the file HISTORY. 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/.