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c945af80cf
Makes the replay loop slightly more readable, by separating the concerns of whether to stop and whether to delay, and how to extract the timestamp from a record. This has the user-visible change that the timestamp of the last applied record is now updated after actually applying it. Before, it was updated just before applying it. That meant that pg_last_xact_replay_timestamp() could return the timestamp of a commit record that is in process of being replayed, but not yet applied. Normally the difference is small, but if min_recovery_apply_delay is set, there could be a significant delay between reading a record and applying it. Another behavioral change is that if you recover to a restore point, we stop after the restore point record, not before it. It makes no difference as far as running queries on the server is concerned, as applying a restore point record changes nothing, but if examine the timeline history you will see that the new timeline branched off just after the restore point record, not before it. One practical consequence is that if you do PITR to the new timeline, and set recovery target to the same named restore point again, it will find and stop recovery at the same restore point. Conceptually, I think it makes more sense to consider the restore point as part of the new timeline's history than not. In principle, setting the last-replayed timestamp before actually applying the record was a bug all along, but it doesn't seem worth the risk to backpatch, since min_recovery_apply_delay was only added in 9.4. |
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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/.