Month: April 2026

Waiting for PostgreSQL 19 – Online enabling and disabling of data checksums

On 3rd of April 2026, Daniel Gustafsson committed patch:

Online enabling and disabling of data checksums
 
This allows data checksums to be enabled, or disabled, in a running
cluster without restricting access to the cluster during processing.
 
Data checksums could prior to this only be enabled during initdb or
when the cluster is offline using the pg_checksums app. This commit
introduce functionality to enable, or disable, data checksums while
the cluster is running regardless of how it was initialized.
 
A background worker launcher process is responsible for launching a
dynamic per-database background worker which will mark all buffers
dirty for all relation with storage in order for them to have data
checksums calculated on write.  Once all relations in all databases
have been processed, the data_checksums state will be set to on and
the cluster will at that point be identical to one which had data
checksums enabled during initialization or via offline processing.
 
When data checksums are being enabled, concurrent I/O operations
from backends other than the data checksums worker will write the
checksums but not verify them on reading.  Only when all backends
have absorbed the procsignalbarrier for setting data_checksums to
on will they also start verifying checksums on reading.  The same
process is repeated during disabling; all backends write checksums
but do not verify them until the barrier for setting the state to
off has been absorbed by all.  This in-progress state is used to
ensure there are no false negatives (or positives) due to reading
a checksum which is not in sync with the page.
 
A new testmodule, test_checksums, is introduced with an extensive
set of tests covering both online and offline data checksum mode
changes.  The tests which run concurrent pgbdench during online
processing are gated behind the PG_TEST_EXTRA flag due to being
very expensive to run.  Two levels of PG_TEST_EXTRA flags exist
to turn on a subset of the expensive tests, or the full suite of
multiple runs.
 
This work is based on an earlier version of this patch which was
reviewed by among others Heikki Linnakangas, Robert Haas, Andres
Freund, Tomas Vondra, Michael Banck and Andrey Borodin.  During
the work on this new version, Tomas Vondra has given invaluable
assistance with not only coding and reviewing but very in-depth
testing.
 
Author: Daniel Gustafsson <daniel@yesql.se>
Author: Magnus Hagander <magnus@hagander.net>
Co-authored-by: Tomas Vondra <tomas@vondra.me>
Reviewed-by: Tomas Vondra <tomas@vondra.me>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://postgr.es/m/CABUevExz9hUUOLnJVr2kpw9Cx=o4MCr1SVKwbupzuxP7ckNutA@mail.gmail.com
Discussion: https://postgr.es/m/20181030051643.elbxjww5jjgnjaxg@alap3.anarazel.de
Discussion: https://postgr.es/m/CABUevEwE3urLtwxxqdgd5O2oQz9J717ZzMbh+ziCSa5YLLU_BA@mail.gmail.com

Continue reading Waiting for PostgreSQL 19 – Online enabling and disabling of data checksums

Waiting for PostgreSQL 19 – new pg_get_*_ddl() functions

On 5th of April 2026, Andrew Dunstan committed patch:

Add pg_get_database_ddl() function
 
Add a new SQL-callable function that returns the DDL statements needed
to recreate a database. It takes a regdatabase argument and an optional
VARIADIC text argument for options that are specified as alternating
name/value pairs. The following options are supported: pretty (boolean)
for formatted output, owner (boolean) to include OWNER and tablespace
(boolean) to include TABLESPACE. The return is one or multiple rows
where the first row is a CREATE DATABASE statement and subsequent rows are
ALTER DATABASE statements to set some database properties.
 
The caller must have CONNECT privilege on the target database.
 
Author: Akshay Joshi <akshay.joshi@enterprisedb.com>
Co-authored-by: Andrew Dunstan <andrew@dunslane.net>
Co-authored-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Quan Zongliang <quanzongliang@yeah.net>
Discussion: https://postgr.es/m/CANxoLDc6FHBYJvcgOnZyS+jF0NUo3Lq_83-rttBuJgs9id_UDg@mail.gmail.com
Discussion: https://postgr.es/m/e247c261-e3fb-4810-81e0-a65893170e94@dunslane.net

and 2nd patch:

Add pg_get_role_ddl() function
 
Add a new SQL-callable function that returns the DDL statements needed
to recreate a role. It takes a regrole argument and an optional VARIADIC
text argument for options that are specified as alternating name/value
pairs. The following options are supported: pretty (boolean) for
formatted output and memberships (boolean) to include GRANT statements
for role memberships and membership options. The return is one or
multiple rows where the first row is a CREATE ROLE statement and
subsequent rows are ALTER ROLE statements to set some role properties.
Password information is never included in the output.
 
The caller must have SELECT privilege on pg_authid.
 
Author: Mario Gonzalez <gonzalemario@gmail.com>
Author: Bryan Green <dbryan.green@gmail.com>
Co-authored-by: Andrew Dunstan <andrew@dunslane.net>
Co-authored-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Reviewed-by: Quan Zongliang <quanzongliang@yeah.net>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://postgr.es/m/4c5f895e-3281-48f8-b943-9228b7da6471@gmail.com
Discussion: https://postgr.es/m/e247c261-e3fb-4810-81e0-a65893170e94@dunslane.net

and then 3rd patch:

Add pg_get_tablespace_ddl() function
 
Add a new SQL-callable function that returns the DDL statements needed
to recreate a tablespace. It takes a tablespace name or OID and an
optional VARIADIC text argument for options that are specified as
alternating name/value pairs. The following options are supported: pretty
(boolean) for formatted output and owner (boolean) to include OWNER.
(It includes two variants because there is no regtablespace pseudotype.)
The return is one or multiple rows where the first row is a CREATE
TABLESPACE statement and subsequent rows are ALTER TABLESPACE statements
to set some tablespace properties.
 
The caller must have SELECT privilege on pg_tablespace.
 
get_reloptions() in ruleutils.c is made non-static so it can be called
from the new ddlutils.c file.
 
Author: Nishant Sharma <nishant.sharma@enterprisedb.com>
Author: Manni Wood <manni.wood@enterprisedb.com>
Co-authored-by: Andrew Dunstan <andrew@dunslane.net>
Co-authored-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Jim Jones <jim.jones@uni-muenster.de>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/CAKWEB6rmnmGKUA87Zmq-s=b3Scsnj02C0kObQjnbL2ajfPWGEw@mail.gmail.com
Discussion: https://postgr.es/m/e247c261-e3fb-4810-81e0-a65893170e94@dunslane.net

Continue reading Waiting for PostgreSQL 19 – new pg_get_*_ddl() functions

Waiting for PostgreSQL 19 – Add UPDATE/DELETE FOR PORTION OF

On 1st of April 2026, Peter Eisentraut committed patch:

Add UPDATE/DELETE FOR PORTION OF
 
This is an extension of the UPDATE and DELETE commands to do a
"temporal update/delete" based on a range or multirange column.  The
user can say UPDATE t FOR PORTION OF valid_at FROM '2001-01-01' TO
'2002-01-01' SET ... (or likewise with DELETE) where valid_at is a
range or multirange column.
 
The command is automatically limited to rows overlapping the targeted
portion, and only history within those bounds is changed.  If a row
represents history partly inside and partly outside the bounds, then
the command truncates the row's application time to fit within the
targeted portion, then it inserts one or more "temporal leftovers":
new rows containing all the original values, except with the
application-time column changed to only represent the untouched part
of history.
 
To compute the temporal leftovers that are required, we use the *_minus_multi
set-returning functions defined in 5eed8ce50c.
 
- Added bison support for FOR PORTION OF syntax.  The bounds must be
  constant, so we forbid column references, subqueries, etc. We do
  accept functions like NOW().
- Added logic to executor to insert new rows for the "temporal
  leftover" part of a record touched by a FOR PORTION OF query.
- Documented FOR PORTION OF.
- Added tests.
 
Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://www.postgresql.org/message-id/flat/ec498c3d-5f2b-48ec-b989-5561c8aa2024%40illuminatedcomputing.com

Continue reading Waiting for PostgreSQL 19 – Add UPDATE/DELETE FOR PORTION OF