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A ReorderBufferTransaction's end_lsn, the sentPtr advocated by walsender keepalive messages, and the end location remembered by the decoding get_*changes* SQL functions all use the location of the last read record + 1. I.e. the LSN points to the beginning of the next record. That cannot realistically be changed without changing the replication protocol because that's how keepalive messages have worked since 9.0. The bug is that the logic inside the snapshot builder, which decides whether a transaction's contents should be decoded, assumed the start location would point towards the last byte of the last record. The reason this didn't actually cause visible problems is that currently that decision is only made for commit records. Since interesting transactions always have at least one additional record - containing actual data - we'd never skip a transaction. But if there ever were transactions, or other events, with just one record containing important information, we'd skip them after stopping and restarting logical decoding.
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/.