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base repository: postgresql-cfbot/postgresql
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  • 4 commits
  • 25 files changed
  • 2 contributors

Commits on Mar 23, 2025

  1. initdb: Add --no-sync-data-files. 

    This new option instructs initdb to skip synchronizing any files
in database directories and the database directories themselves,
i.e., everything in the base/ subdirectory and any other
tablespace directories.  Other files, such as those in pg_wal/ and
pg_xact/, will still be synchronized unless --no-sync is also
specified.  --no-sync-data-files is primarily intended for internal
use by tools that separately ensure the skipped files are
synchronized to disk.  A follow-up commit will use this to help
optimize pg_upgrade's file transfer step.

Reviewed-by: Greg Sabino Mullane <[email protected]>
Reviewed-by: Bruce Momjian <[email protected]>
Reviewed-by: Robert Haas <[email protected]>
Discussion: https://postgr.es/m/Zyvop-LxLXBLrZil%40nathan
    @nathan-bossart
    nathan-bossart authored and Commitfest Bot committed Mar 23, 2025
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  2. pg_dump: Add --sequence-data. 

    This new option instructs pg_dump to dump sequence data when the
--no-data, --schema-only, or --statistics-only option is specified.
This was originally considered for commit a7e5457, but it was
left out at that time because there was no known use-case.  A
follow-up commit will use this to optimize pg_upgrade's file
transfer step.

Reviewed-by: Greg Sabino Mullane <[email protected]>
Reviewed-by: Bruce Momjian <[email protected]>
Reviewed-by: Robert Haas <[email protected]>
Discussion: https://postgr.es/m/Zyvop-LxLXBLrZil%40nathan
    @nathan-bossart
    nathan-bossart authored and Commitfest Bot committed Mar 23, 2025
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  3. pg_upgrade: Add --swap for faster file transfer. 

    This new option instructs pg_upgrade to move the data directories
from the old cluster to the new cluster and then to replace the
catalog files with those generated for the new cluster.  This mode
can outperform --link, --clone, --copy, and --copy-file-range,
especially on clusters with many relations.

However, this mode creates many garbage files in the old cluster,
which can prolong the file synchronization step.  To handle that,
we use "initdb --sync-only --no-sync-data-files" for file
synchronization, and we synchronize the catalog files as they are
transferred.  We assume that the database files transferred from
the old cluster were synchronized prior to upgrade.

This mode also complicates reverting to the old cluster, so we
recommend restoring from backup upon failure during or after file
transfer.  We did consider teaching pg_upgrade how to generate a
revert script for such failures, but we decided against it due to
the rarity of failing during file transfer, the complexity of
generating the script, and the potential for misusing the script.

The new mode is limited to clusters located in the same file
system.  With some effort, we could probably support upgrades
between different file systems, but this mode is unlikely to offer
much benefit if we have to copy the files across file system
boundaries.

It is also limited to upgrades from version 10 or newer.  There are
a few known obstacles for using swap mode to upgrade from older
versions.  For example, the visibility map format changed in v9.6,
and the sequence tuple format changed in v10.  In fact, swap mode
omits the --sequence-data option in its uses of pg_dump and instead
reuses the old cluster's sequence data files.  While teaching swap
mode to deal with these kinds of changes is surely possible (and we
may have to deal with similar problems in the future, anyway), it
doesn't seem worth the effort to support upgrades from
long-unsupported versions.

Reviewed-by: Greg Sabino Mullane <[email protected]>
Reviewed-by: Bruce Momjian <[email protected]>
Reviewed-by: Robert Haas <[email protected]>
Discussion: https://postgr.es/m/Zyvop-LxLXBLrZil%40nathan
    @nathan-bossart
    nathan-bossart authored and Commitfest Bot committed Mar 23, 2025
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  4. [CF 5369] v9 - optimize file transfer in pg_upgrade 

    This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/5369

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/Z9x5MVjWO7zVwrJ0@nathan
Author(s): Nathan Bossart
    Commitfest Bot committed Mar 23, 2025
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