Fix corruption of templates after CREATE DATABASE .. STRATEGY WAL_LOG
WAL_LOG does a scan of the template's pg_class to determine the set of
relations that need to be copied from a template database to the new
one. However, as coded in 9c08aea, this copy strategy would load the
pages of pg_class without considering it as a permanent relation,
causing the loaded pages to never be flushed when they should. Any
modification of the template's pg_class, mostly through DDLs, would then
be missed, causing corruptions.
STRATEGY = WAL_LOG is the default over FILE_COPY since it has been
introduced, so any changes done to pg_class on a database template would
be gone. Updates of database templates should be a rare thing, so the
impact of this bug should be hopefully limited. The pre-14 default
strategy FILE_COPY is safe, and can be used as a workaround.
Ryo Matsumura has found and analyzed the issue, and Nathan has written a
test able to reproduce the failure (with few tweaks from me).
Backpatch down to 15, where STRATEGY = WAL_LOG has been introduced.
Author: Nathan Bossart, Ryo Matsumura
Reviewed-by: Dilip Kumar, Michael Paquier
Discussion: https://postgr.es/m/TYCPR01MB6868677E499C9AD5123084B5E8A39@TYCPR01MB6868.jpnprd01.prod.outlook.com
Backpatch-through: 15
Branch
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master
Details
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https://git.postgresql.org/pg/commitdiff/8a8661828ae14e4d3b6beac5e8d8b37bd4e79004
Modified Files
--------------
src/backend/commands/dbcommands.c | 2 +-
src/test/recovery/meson.build | 1 +
src/test/recovery/t/034_create_database.pl | 45 ++++++++++++++++++++++++++++++
3 files changed, 47 insertions(+), 1 deletion(-)