From 293913568e6a7a86fd1479e1cff8e2ecb58d6568 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 13 Apr 2024 15:44:03 +0200 Subject: Adding upstream version 16.2. Signed-off-by: Daniel Baumann --- doc/src/sgml/html/logicaldecoding-synchronous.html | 50 ++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 doc/src/sgml/html/logicaldecoding-synchronous.html (limited to 'doc/src/sgml/html/logicaldecoding-synchronous.html') diff --git a/doc/src/sgml/html/logicaldecoding-synchronous.html b/doc/src/sgml/html/logicaldecoding-synchronous.html new file mode 100644 index 0000000..bee0170 --- /dev/null +++ b/doc/src/sgml/html/logicaldecoding-synchronous.html @@ -0,0 +1,50 @@ + +49.8. Synchronous Replication Support for Logical Decoding
49.8. Synchronous Replication Support for Logical Decoding
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49.8. Synchronous Replication Support for Logical Decoding #

49.8.1. Overview
49.8.2. Caveats

49.8.1. Overview #

+ Logical decoding can be used to build + synchronous + replication solutions with the same user interface as synchronous + replication for streaming + replication. To do this, the streaming replication interface + (see Section 49.3) must be used to stream out + data. Clients have to send Standby status update (F) + (see Section 55.4) messages, just like streaming + replication clients do. +

Note

+ A synchronous replica receiving changes via logical decoding will work in + the scope of a single database. Since, in contrast to + that, synchronous_standby_names currently is + server wide, this means this technique will not work properly if more + than one database is actively used. +

49.8.2. Caveats #

+ In synchronous replication setup, a deadlock can happen, if the transaction + has locked [user] catalog tables exclusively. See + Section 49.6.2 for information on user + catalog tables. This is because logical decoding of transactions can lock + catalog tables to access them. To avoid this users must refrain from taking + an exclusive lock on [user] catalog tables. This can happen in the following + ways: + +

  • + Issuing an explicit LOCK on pg_class + in a transaction. +

  • + Perform CLUSTER on pg_class in + a transaction. +

  • + PREPARE TRANSACTION after LOCK command + on pg_class and allow logical decoding of two-phase + transactions. +

  • + PREPARE TRANSACTION after CLUSTER + command on pg_trigger and allow logical decoding of + two-phase transactions. This will lead to deadlock only when published table + have a trigger. +

  • + Executing TRUNCATE on [user] catalog table in a + transaction. +

+ + Note that these commands that can cause deadlock apply to not only explicitly + indicated system catalog tables above but also to any other [user] catalog + table. +

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49.7. Logical Decoding Output Writers Home 49.9. Streaming of Large Transactions for Logical Decoding
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