A bunch of tests missed specifying that empty transactions shouldn't be
displayed. That causes problems when e.g. autovacuum runs in an
unfortunate moment. The tests in question only run for a very short
time, making this quite unlikely.
Reported-By: Buildfarm member axolotl
Backpatch: 9.4, where logical decoding was introduced
Commit 6f37c08057 removed whitespace
from the SQL file but not the expected-output file, and commit
7e8db2dc42 changed the error message
without updating the expected outputs.
This feature, building on previous commits, allows the write-ahead log
stream to be decoded into a series of logical changes; that is,
inserts, updates, and deletes and the transactions which contain them.
It is capable of handling decoding even across changes to the schema
of the effected tables. The output format is controlled by a
so-called "output plugin"; an example is included. To make use of
this in a real replication system, the output plugin will need to be
modified to produce output in the format appropriate to that system,
and to perform filtering.
Currently, information can be extracted from the logical decoding
system only via SQL; future commits will add the ability to stream
changes via walsender.
Andres Freund, with review and other contributions from many other
people, including Álvaro Herrera, Abhijit Menon-Sen, Peter Gheogegan,
Kevin Grittner, Robert Haas, Heikki Linnakangas, Fujii Masao, Abhijit
Menon-Sen, Michael Paquier, Simon Riggs, Craig Ringer, and Steve
Singer.
Peter Eisentraut
Andres Freund
Robert Haas