digoal
2021-07-14
PostgreSQL , 逻辑复制 , sub , pub
Add support for prepared transactions to built-in logical replication.
master github/master
author Amit Kapila <akapila@postgresql.org>
Wed, 14 Jul 2021 02:03:50 +0000 (07:33 +0530)
committer Amit Kapila <akapila@postgresql.org>
Wed, 14 Jul 2021 02:03:50 +0000 (07:33 +0530)
commit a8fd13cab0ba815e9925dc9676e6309f699b5f72
tree bfebac6bfc2d32a9212e33f9090bd700b0316fae tree
parent 6c9c2831668345122fd0f92280b30f3bbe2dd4e6 commit | diff
Add support for prepared transactions to built-in logical replication.
To add support for streaming transactions at prepare time into the
built-in logical replication, we need to do the following things:
* Modify the output plugin (pgoutput) to implement the new two-phase API
callbacks, by leveraging the extended replication protocol.
* Modify the replication apply worker, to properly handle two-phase
transactions by replaying them on prepare.
* Add a new SUBSCRIPTION option "two_phase" to allow users to enable
two-phase transactions. We enable the two_phase once the initial data sync
is over.
We however must explicitly disable replication of two-phase transactions
during replication slot creation, even if the plugin supports it. We
don't need to replicate the changes accumulated during this phase,
and moreover, we don't have a replication connection open so we don't know
where to send the data anyway.
The streaming option is not allowed with this new two_phase option. This
can be done as a separate patch.
We don't allow to toggle two_phase option of a subscription because it can
lead to an inconsistent replica. For the same reason, we don't allow to
refresh the publication once the two_phase is enabled for a subscription
unless copy_data option is false.
Author: Peter Smith, Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich
Reviewed-by: Amit Kapila, Sawada Masahiko, Vignesh C, Dilip Kumar, Takamichi Osumi, Greg Nancarrow
Tested-By: Haiying Tang
Discussion: https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru
Discussion: https://postgr.es/m/CAA4eK1+opiV4aFTmWWUF9h_32=HfPOW9vZASHarT0UA5oBrtGw@mail.gmail.com
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