postgres

Commit Graph

Author	SHA1	Message	Date
Amit Kapila	ddd5f4f54a	Add a slot synchronization function. This commit introduces a new SQL function pg_sync_replication_slots() which is used to synchronize the logical replication slots from the primary server to the physical standby so that logical replication can be resumed after a failover or planned switchover. A new 'synced' flag is introduced in pg_replication_slots view, indicating whether the slot has been synchronized from the primary server. On a standby, synced slots cannot be dropped or consumed, and any attempt to perform logical decoding on them will result in an error. The logical replication slots on the primary can be synchronized to the hot standby by using the 'failover' parameter of pg-create-logical-replication-slot(), or by using the 'failover' option of CREATE SUBSCRIPTION during slot creation, and then calling pg_sync_replication_slots() on standby. For the synchronization to work, it is mandatory to have a physical replication slot between the primary and the standby aka 'primary_slot_name' should be configured on the standby, and 'hot_standby_feedback' must be enabled on the standby. It is also necessary to specify a valid 'dbname' in the 'primary_conninfo'. If a logical slot is invalidated on the primary, then that slot on the standby is also invalidated. If a logical slot on the primary is valid but is invalidated on the standby, then that slot is dropped but will be recreated on the standby in the next pg_sync_replication_slots() call provided the slot still exists on the primary server. It is okay to recreate such slots as long as these are not consumable on standby (which is the case currently). This situation may occur due to the following reasons: - The 'max_slot_wal_keep_size' on the standby is insufficient to retain WAL records from the restart_lsn of the slot. - 'primary_slot_name' is temporarily reset to null and the physical slot is removed. The slot synchronization status on the standby can be monitored using the 'synced' column of pg_replication_slots view. A functionality to automatically synchronize slots by a background worker and allow logical walsenders to wait for the physical will be done in subsequent commits. Author: Hou Zhijie, Shveta Malik, Ajin Cherian based on an earlier version by Peter Eisentraut Reviewed-by: Masahiko Sawada, Bertrand Drouvot, Peter Smith, Dilip Kumar, Nisha Moond, Kuroda Hayato, Amit Kapila Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com	2 years ago
Tom Lane	18555b1323	Establish conventions about global object names used in regression tests. To ensure that "make installcheck" can be used safely against an existing installation, we need to be careful about what global object names (database, role, and tablespace names) we use; otherwise we might accidentally clobber important objects. There's been a weak consensus that test databases should have names including "regression", and that test role names should start with "regress_", but we didn't have any particular rule about tablespace names; and neither of the other rules was followed with any consistency either. This commit moves us a long way towards having a hard-and-fast rule that regression test databases must have names including "regression", and that test role and tablespace names must start with "regress_". It's not completely there because I did not touch some test cases in rolenames.sql that test creation of special role names like "session_user". That will require some rethinking of exactly what we want to test, whereas the intent of this patch is just to hit all the cases in which the needed renamings are cosmetic. There is no enforcement mechanism in this patch either, but if we don't add one we can expect that the tests will soon be violating the convention again. Again, that's not such a cosmetic change and it will require discussion. (But I did use a quick-hack enforcement patch to find these cases.) Discussion: <16638.1468620817@sss.pgh.pa.us>	10 years ago
Andres Freund	d6fa44fce7	Add skip-empty-xacts option to test_decoding for use in the regression tests. The regression tests for contrib/test_decoding regularly failed on postgres instances that were very slow. Either because the hardware itself was slow or because very expensive debugging options like CLOBBER_CACHE_ALWAYS were used. The reason they failed was just that some additional transactions were decoded. Analyze and vacuum, triggered by autovac. To fix just add a option to test_decoding to only display transactions in which a change was actually displayed. That's not pretty because it removes information from the tests; but better than constantly failing tests in very likely harmless ways. Backpatch to 9.4 where logical decoding was introduced. Discussion: 20140629142511.GA26930@awork2.anarazel.de	12 years ago
Robert Haas	b89e151054	Introduce logical decoding. 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.	12 years ago

4 Commits (ae627d8a3cb046379e90295bcf85c9fc6432841a)