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Subject: BUG #19439: pg_stat_xact_user_tables stat not currect during the transaction
To: pgsql-bugs@lists.postgresql.org
From: PG Bug reporting form <noreply@postgresql.org>
Cc: klemen.kobau@gmail.com
Reply-To: klemen.kobau@gmail.com, pgsql-bugs@lists.postgresql.org
Date: Wed, 25 Mar 2026 14:06:37 +0000
Message-ID: <19439-8f02018f9fc3a240@postgresql.org>
Auto-Submitted: auto-generated
Archived-At: <https://www.postgresql.org/message-id/19439-8f02018f9fc3a240%40postgresql.org>
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The following bug has been logged on the website:

Bug reference:      19439
Logged by:          klemen kobau
Email address:      klemen.kobau@gmail.com
PostgreSQL version: 18.0
Operating system:   Linux (EndeavorOS)
Description:       =20

I am running postgres:18.0 in a docker container, the configuration is as
follows:

  postgres:
    image: postgres:18.0
    command: [
      "postgres",
      "-N", "200",
      "-c", "max_prepared_transactions=3D100",
      "-c", "wal_level=3Dlogical",
      "-c", "max_wal_senders=3D10",
      "-c", "max_replication_slots=3D20",
      "-c", "wal_keep_size=3D10",
      "-c", "max_slot_wal_keep_size=3D1024"
    ]
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: postgres
      TZ: UTC
      PGTZ: UTC
    ports:
      - 5432:5432
    volumes:
      - postgres_data:/var/lib/postgresql

I use psql version 18.3.

I run the following:

psql -h localhost -p 5432 -U postgres -d postgres -c "
-- Transaction 1: insert 1 row, check stats, commit
BEGIN;
CREATE TABLE IF NOT EXISTS temp.xact_test (id serial PRIMARY KEY, val text);
INSERT INTO temp.xact_test (val) VALUES ('a');
SELECT relname, n_tup_ins FROM pg_stat_xact_user_tables WHERE relname =3D
'xact_test';
COMMIT;

-- Transaction 2: insert 1 row, check stats
BEGIN;
INSERT INTO temp.xact_test (val) VALUES ('b');
SELECT relname, n_tup_ins FROM pg_stat_xact_user_tables WHERE relname =3D
'xact_test';
ROLLBACK;

-- Cleanup
DROP TABLE temp.xact_test;
"

And the output is

BEGIN
CREATE TABLE
INSERT 0 1
  relname  | n_tup_ins
-----------+-----------
 xact_test |         1
(1 row)

COMMIT
BEGIN
INSERT 0 1
  relname  | n_tup_ins
-----------+-----------
 xact_test |         2
(1 row)

ROLLBACK
DROP TABLE

This is not what I would expect from reading
https://www.postgresql.org/docs/current/monitoring-stats.html#MONITORING-ST=
ATS-VIEWS,
where it states

> A transaction can also see its own statistics (not yet flushed out to the
shared memory statistics) in the views pg_stat_xact_all_tables,
pg_stat_xact_sys_tables, pg_stat_xact_user_tables, and
pg_stat_xact_user_functions. These numbers do not act as stated above;
instead they update continuously throughout the transaction.

based on this, I would expect that the numbers are updated each time an
insert happens and that they are isolated per transaction.

Kind regards

Klemen Kobau