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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Kirill Reshke <reshkekirill@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: relfilenode statistics
Date: Fri, 7 Nov 2025 11:28:27 +0000
Message-ID: <aQ3X20hbqoThQXgp@ip-10-97-1-34.eu-west-3.compute.internal> (raw)
In-Reply-To: <aN3T_5NBv0XKFbs7@paquier.xyz>
References: <Z0nbomp2e/L30WDA@ip-10-97-1-34.eu-west-3.compute.internal>
	<CALdSSPhFaLEWXG9Mn8-tZoS68rE52647a2oZ6jrUNSBtwadD0A@mail.gmail.com>
	<Z07d850Yp7Sd9Qqq@ip-10-97-1-34.eu-west-3.compute.internal>
	<Z3gN3bwUMijyV4I0@ip-10-97-1-34.eu-west-3.compute.internal>
	<CALdSSPh76=ACN=z68oM44ZMgZsQxTTYVF8qvi1F6TGA5Mn6uiQ@mail.gmail.com>
	<aMkHSeitgUPtMyA2@paquier.xyz>
	<aNutZbziBycskOYR@ip-10-97-1-34.eu-west-3.compute.internal>
	<aNxiLG0JTCYnpqx6@paquier.xyz>
	<aN07p71KNFR2HdaD@ip-10-97-1-34.eu-west-3.compute.internal>
	<aN3T_5NBv0XKFbs7@paquier.xyz>

Hi,

On Thu, Oct 02, 2025 at 10:23:11AM +0900, Michael Paquier wrote:
> On Wed, Oct 01, 2025 at 02:33:11PM +0000, Bertrand Drouvot wrote:
> > I think the first step is to replace (i.e get rid) PGSTAT_KIND_RELATION by a brand
> > new PGSTAT_KIND_RELFILENODE and move all the existing stats that are currently
> > under the PGSTAT_KIND_RELATION to this new PGSTAT_KIND_RELFILENODE.
> 
> Likely so, yes.

PFA the new implementation. It does not introduce a new PGSTAT_KIND_RELFILENODE,
instead it keys the PGSTAT_KIND_RELATION by relfile locator. We may want to
rename PGSTAT_KIND_RELATION to PGSTAT_KIND_RELFILENODE as a next step.

The patch is structured that way:

==== 0001

Add stats tests related to rewrite

While there are existing rewrite tests, the stats behavior during rewrites
doesn't have a good coverage. This patch adds some tests to record some stats
after different rewrite scenarios.

That way, we'll be able to test that the stats are still the ones we
expect after rewrites. Note that it generates a new stats_1.out (which is quite
large), so we may want to move those new tests to "isolation" instead.

==== 0002

Key PGSTAT_KIND_RELATION by relfile locator

This patch changes the key used for the PGSTAT_KIND_RELATION statistic kind.
Instead of the relation oid, it now relies on:

- dboid (linked to RelFileLocator's dbOid)
- objoid which is the result of a new macro (namely RelFileLocatorToPgStatObjid())
that computes an objoid based on the RelFileLocator's spcOid and the RelFileLocator's
relNumber.

That will allow us to add new stats (add writes counters) and ensure that some
counters (n_dead_tup and friends) are replicated.

The patch introduces pgstat_reloid_to_relfilelocator() to 1) avoid calling
RelationIdGetRelation() to get the relfilelocator based on the relation oid
and 2) handle the partitioned table case.

Please note that:

- when running pg_stat_have_stats('relation',...) we now need to be connected
to the database that hosts the relation. As pg_stat_have_stats() is not
documented publicly, then the changes done in 029_stats_restart.pl look
enough.

- this patch does not handle rewrites so some tests are failing. It's only
intent is to ease the review and should not be pushed without being
merged with the following patch that handles the rewrites.

- it can be used to test that stats are incremented correctly and that we're
able to retrieve them as long as rewrites are not involved.

==== 0003

handle relation statistics correctly during rewrites

Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.

To do so, this patch:

- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.

- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.

- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).

- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.

Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.

The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.

Another design that I tried was to copy the stats in pgstat_mark_rewrite() but
that lead to difficulties during abort, subtransactions. It looks to me that
the list approach proposed here makes more sense.

We could also imagine adding a function similar to pg_stat_have_stats() that
would take relfile locator as arguments. That could help validate that after
a rewrite the old stats are gone.
 
> Do you think it is OK to define non-transactional pending stats as
> being always a subset of the transactional stats?  I don't quite see 
> if there would be a case to have stats that are only flushed in a
> non-transactional path, while being discarded at the stats report done
> at transaction commit time.  This means that it may be possible to
> structure things so as the pending non-transaction stats structure are
> always part of the transactional bits, and that the other way around
> is not possible.  Perhaps that influences the design choices, at least
> a bit.

The proposed patch does not change anything it that regard.
It keeps the relation's behavior as it is.

This patch just ensure that a relation rewrite keeps its stats.

Adding new stats (add writes counters) and ensure that some counters
(n_dead_tup and friends) are replicated will be done once this one gets in.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

Attachments:

  [text/x-diff] v7-0001-Add-stats-tests-related-to-rewrite.patch (85.6K, ../aQ3X20hbqoThQXgp@ip-10-97-1-34.eu-west-3.compute.internal/2-v7-0001-Add-stats-tests-related-to-rewrite.patch)
  download | inline diff:
From 40903079d2f011e6fb33045d7b36b1014fc7a981 Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Date: Mon, 27 Oct 2025 14:54:23 +0000
Subject: [PATCH v7 1/3] Add stats tests related to rewrite

While there are existing rewrite tests, the stats behavior during rewrites
doesn't have a good coverage. This patch adds some tests to record some stats after
different rewrite scenarios.

That is useful for a following patch where relation statistics will be keyed
by relfilenode. We'll be able to test that the stats are still the ones we
expect after rewrites.
---
 src/test/regress/expected/stats.out   |  321 ++++
 src/test/regress/expected/stats_1.out | 2255 +++++++++++++++++++++++++
 src/test/regress/sql/stats.sql        |  186 ++
 3 files changed, 2762 insertions(+)
  91.8% src/test/regress/expected/
   8.1% src/test/regress/sql/

diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 67e1860e984..06487e367d8 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -1910,4 +1910,325 @@ SELECT * FROM check_estimated_rows('SELECT * FROM table_fillfactor');
 (1 row)
 
 DROP TABLE table_fillfactor;
+-- Test some rewrites
+CREATE TABLE test_2pc_timestamp (a int) WITH (autovacuum_enabled = false);
+VACUUM ANALYZE test_2pc_timestamp;
+SELECT last_analyze AS last_vacuum_analyze FROM pg_stat_all_tables WHERE relname = 'test_2pc_timestamp' \gset
+BEGIN;
+ALTER TABLE test_2pc_timestamp ALTER COLUMN a TYPE int;
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT last_analyze = :'last_vacuum_analyze'::timestamptz FROM pg_stat_all_tables WHERE relname = 'test_2pc_timestamp';
+ ?column? 
+----------
+ t
+(1 row)
+
+DROP TABLE test_2pc_timestamp;
+CREATE TABLE test_2pc_rewrite_alone (a int);
+INSERT INTO test_2pc_rewrite_alone VALUES (1);
+BEGIN;
+ALTER TABLE test_2pc_rewrite_alone ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_rewrite_alone';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_2pc_rewrite_alone;
+CREATE TABLE test_2pc (a int);
+INSERT INTO test_2pc VALUES (1);
+BEGIN;
+INSERT INTO test_2pc VALUES (1);
+INSERT INTO test_2pc VALUES (2);
+INSERT INTO test_2pc VALUES (3);
+ALTER TABLE test_2pc ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         4 |          4 |          0
+(1 row)
+
+DROP TABLE test_2pc;
+CREATE TABLE test_2pc_multi (a int);
+INSERT INTO test_2pc_multi VALUES (1);
+BEGIN;
+INSERT INTO test_2pc_multi VALUES (1);
+INSERT INTO test_2pc_multi VALUES (2);
+ALTER TABLE test_2pc_multi ALTER COLUMN a TYPE bigint;
+INSERT INTO test_2pc_multi VALUES (3);
+INSERT INTO test_2pc_multi VALUES (4);
+ALTER TABLE test_2pc_multi ALTER COLUMN a TYPE int;
+INSERT INTO test_2pc_multi VALUES (5);
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_multi';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         6 |          6 |          0
+(1 row)
+
+DROP TABLE test_2pc_multi;
+CREATE TABLE test_2pc_rewrite_alone_abort (a int);
+INSERT INTO test_2pc_rewrite_alone_abort VALUES (1);
+BEGIN;
+ALTER TABLE test_2pc_rewrite_alone_abort ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+ROLLBACK PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_rewrite_alone_abort';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_2pc_rewrite_alone_abort;
+CREATE TABLE test_2pc_abort (a int);
+INSERT INTO test_2pc_abort VALUES (1);
+BEGIN;
+INSERT INTO test_2pc_abort VALUES (1);
+INSERT INTO test_2pc_abort VALUES (2);
+ALTER TABLE test_2pc_abort ALTER COLUMN a TYPE bigint;
+INSERT INTO test_2pc_abort VALUES (3);
+PREPARE TRANSACTION 'test';
+ROLLBACK PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_abort';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         4 |          1 |          3
+(1 row)
+
+DROP TABLE test_2pc_abort;
+CREATE TABLE test_2pc_savepoint (a int);
+INSERT INTO test_2pc_savepoint VALUES (1);
+BEGIN;
+SAVEPOINT a;
+INSERT INTO test_2pc_savepoint VALUES (1);
+INSERT INTO test_2pc_savepoint VALUES (2);
+ALTER TABLE test_2pc_savepoint ALTER COLUMN a TYPE bigint;
+SAVEPOINT b;
+INSERT INTO test_2pc_savepoint VALUES (3);
+ALTER TABLE test_2pc_savepoint ALTER COLUMN a TYPE int;
+SAVEPOINT c;
+INSERT INTO test_2pc_savepoint VALUES (4);
+INSERT INTO test_2pc_savepoint VALUES (5);
+ROLLBACK TO SAVEPOINT b;
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_savepoint';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         6 |          3 |          3
+(1 row)
+
+DROP TABLE test_2pc_savepoint;
+-- Rewrite without 2PC
+CREATE TABLE test_timestamp (a int) WITH (autovacuum_enabled = false);
+VACUUM ANALYZE test_timestamp;
+SELECT last_analyze AS last_vacuum_analyze FROM pg_stat_all_tables WHERE relname = 'test_timestamp' \gset
+ALTER TABLE test_timestamp ALTER COLUMN a TYPE bigint;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT last_analyze = :'last_vacuum_analyze'::timestamptz FROM pg_stat_all_tables WHERE relname = 'test_timestamp';
+ ?column? 
+----------
+ t
+(1 row)
+
+DROP TABLE test_timestamp;
+CREATE TABLE test_alone (a int);
+INSERT INTO test_alone VALUES (1);
+BEGIN;
+ALTER TABLE test_alone ALTER COLUMN a TYPE bigint;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_alone';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_alone;
+CREATE TABLE test (a int);
+INSERT INTO test VALUES (1);
+BEGIN;
+INSERT INTO test VALUES (1);
+INSERT INTO test VALUES (2);
+INSERT INTO test VALUES (3);
+ALTER TABLE test ALTER COLUMN a TYPE bigint;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         4 |          4 |          0
+(1 row)
+
+DROP TABLE test;
+CREATE TABLE test_multi (a int);
+INSERT INTO test_multi VALUES (1);
+BEGIN;
+INSERT INTO test_multi VALUES (1);
+INSERT INTO test_multi VALUES (2);
+ALTER TABLE test_multi ALTER COLUMN a TYPE bigint;
+INSERT INTO test_multi VALUES (3);
+INSERT INTO test_multi VALUES (4);
+ALTER TABLE test_multi ALTER COLUMN a TYPE int;
+INSERT INTO test_multi VALUES (5);
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_multi';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         6 |          6 |          0
+(1 row)
+
+DROP TABLE test_multi;
+CREATE TABLE test_rewrite_alone_abort (a int);
+INSERT INTO test_rewrite_alone_abort VALUES (1);
+BEGIN;
+ALTER TABLE test_rewrite_alone_abort ALTER COLUMN a TYPE bigint;
+ROLLBACK;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_rewrite_alone_abort';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_rewrite_alone_abort;
+CREATE TABLE test_abort (a int);
+INSERT INTO test_abort VALUES (1);
+BEGIN;
+INSERT INTO test_abort VALUES (1);
+INSERT INTO test_abort VALUES (2);
+ALTER TABLE test_abort ALTER COLUMN a TYPE bigint;
+INSERT INTO test_abort VALUES (3);
+ROLLBACK;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_abort';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         4 |          1 |          3
+(1 row)
+
+DROP TABLE test_abort;
+CREATE TABLE test_savepoint (a int);
+INSERT INTO test_savepoint VALUES (1);
+BEGIN;
+SAVEPOINT a;
+INSERT INTO test_savepoint VALUES (1);
+INSERT INTO test_savepoint VALUES (2);
+ALTER TABLE test_savepoint ALTER COLUMN a TYPE bigint;
+SAVEPOINT b;
+INSERT INTO test_savepoint VALUES (3);
+ALTER TABLE test_savepoint ALTER COLUMN a TYPE int;
+SAVEPOINT c;
+INSERT INTO test_savepoint VALUES (4);
+INSERT INTO test_savepoint VALUES (5);
+ROLLBACK TO SAVEPOINT b;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_savepoint';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         6 |          3 |          3
+(1 row)
+
+DROP TABLE test_savepoint;
+CREATE TABLE test_tbs (a int);
+INSERT INTO test_tbs VALUES (1);
+ALTER TABLE test_tbs SET TABLESPACE pg_default;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_tbs';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_tbs;
 -- End of Stats Test
diff --git a/src/test/regress/expected/stats_1.out b/src/test/regress/expected/stats_1.out
new file mode 100644
index 00000000000..629e71fce0d
--- /dev/null
+++ b/src/test/regress/expected/stats_1.out
@@ -0,0 +1,2255 @@
+--
+-- Test cumulative stats system
+--
+-- Must be run after tenk2 has been created (by create_table),
+-- populated (by create_misc) and indexed (by create_index).
+--
+-- conditio sine qua non
+SHOW track_counts;  -- must be on
+ track_counts 
+--------------
+ on
+(1 row)
+
+-- List of backend types, contexts and objects tracked in pg_stat_io.
+\a
+SELECT backend_type, object, context FROM pg_stat_io
+  ORDER BY backend_type COLLATE "C", object COLLATE "C", context COLLATE "C";
+backend_type|object|context
+autovacuum launcher|relation|bulkread
+autovacuum launcher|relation|init
+autovacuum launcher|relation|normal
+autovacuum launcher|wal|init
+autovacuum launcher|wal|normal
+autovacuum worker|relation|bulkread
+autovacuum worker|relation|init
+autovacuum worker|relation|normal
+autovacuum worker|relation|vacuum
+autovacuum worker|wal|init
+autovacuum worker|wal|normal
+background worker|relation|bulkread
+background worker|relation|bulkwrite
+background worker|relation|init
+background worker|relation|normal
+background worker|relation|vacuum
+background worker|temp relation|normal
+background worker|wal|init
+background worker|wal|normal
+background writer|relation|init
+background writer|relation|normal
+background writer|wal|init
+background writer|wal|normal
+checkpointer|relation|init
+checkpointer|relation|normal
+checkpointer|wal|init
+checkpointer|wal|normal
+client backend|relation|bulkread
+client backend|relation|bulkwrite
+client backend|relation|init
+client backend|relation|normal
+client backend|relation|vacuum
+client backend|temp relation|normal
+client backend|wal|init
+client backend|wal|normal
+io worker|relation|bulkread
+io worker|relation|bulkwrite
+io worker|relation|init
+io worker|relation|normal
+io worker|relation|vacuum
+io worker|temp relation|normal
+io worker|wal|init
+io worker|wal|normal
+slotsync worker|relation|bulkread
+slotsync worker|relation|bulkwrite
+slotsync worker|relation|init
+slotsync worker|relation|normal
+slotsync worker|relation|vacuum
+slotsync worker|temp relation|normal
+slotsync worker|wal|init
+slotsync worker|wal|normal
+standalone backend|relation|bulkread
+standalone backend|relation|bulkwrite
+standalone backend|relation|init
+standalone backend|relation|normal
+standalone backend|relation|vacuum
+standalone backend|wal|init
+standalone backend|wal|normal
+startup|relation|bulkread
+startup|relation|bulkwrite
+startup|relation|init
+startup|relation|normal
+startup|relation|vacuum
+startup|wal|init
+startup|wal|normal
+walreceiver|wal|init
+walreceiver|wal|normal
+walsender|relation|bulkread
+walsender|relation|bulkwrite
+walsender|relation|init
+walsender|relation|normal
+walsender|relation|vacuum
+walsender|temp relation|normal
+walsender|wal|init
+walsender|wal|normal
+walsummarizer|wal|init
+walsummarizer|wal|normal
+walwriter|wal|init
+walwriter|wal|normal
+(79 rows)
+\a
+-- ensure that both seqscan and indexscan plans are allowed
+SET enable_seqscan TO on;
+SET enable_indexscan TO on;
+-- for the moment, we don't want index-only scans here
+SET enable_indexonlyscan TO off;
+-- not enabled by default, but we want to test it...
+SET track_functions TO 'all';
+-- record dboid for later use
+SELECT oid AS dboid from pg_database where datname = current_database() \gset
+-- save counters
+BEGIN;
+SET LOCAL stats_fetch_consistency = snapshot;
+CREATE TABLE prevstats AS
+SELECT t.seq_scan, t.seq_tup_read, t.idx_scan, t.idx_tup_fetch,
+       (b.heap_blks_read + b.heap_blks_hit) AS heap_blks,
+       (b.idx_blks_read + b.idx_blks_hit) AS idx_blks,
+       pg_stat_get_snapshot_timestamp() as snap_ts
+  FROM pg_catalog.pg_stat_user_tables AS t,
+       pg_catalog.pg_statio_user_tables AS b
+ WHERE t.relname='tenk2' AND b.relname='tenk2';
+COMMIT;
+-- test effects of TRUNCATE on n_live_tup/n_dead_tup counters
+CREATE TABLE trunc_stats_test(id serial);
+CREATE TABLE trunc_stats_test1(id serial, stuff text);
+CREATE TABLE trunc_stats_test2(id serial);
+CREATE TABLE trunc_stats_test3(id serial, stuff text);
+CREATE TABLE trunc_stats_test4(id serial);
+-- check that n_live_tup is reset to 0 after truncate
+INSERT INTO trunc_stats_test DEFAULT VALUES;
+INSERT INTO trunc_stats_test DEFAULT VALUES;
+INSERT INTO trunc_stats_test DEFAULT VALUES;
+TRUNCATE trunc_stats_test;
+-- test involving a truncate in a transaction; 4 ins but only 1 live
+INSERT INTO trunc_stats_test1 DEFAULT VALUES;
+INSERT INTO trunc_stats_test1 DEFAULT VALUES;
+INSERT INTO trunc_stats_test1 DEFAULT VALUES;
+UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
+DELETE FROM trunc_stats_test1 WHERE id = 3;
+BEGIN;
+UPDATE trunc_stats_test1 SET id = id + 100;
+TRUNCATE trunc_stats_test1;
+INSERT INTO trunc_stats_test1 DEFAULT VALUES;
+COMMIT;
+-- use a savepoint: 1 insert, 1 live
+BEGIN;
+INSERT INTO trunc_stats_test2 DEFAULT VALUES;
+INSERT INTO trunc_stats_test2 DEFAULT VALUES;
+SAVEPOINT p1;
+INSERT INTO trunc_stats_test2 DEFAULT VALUES;
+TRUNCATE trunc_stats_test2;
+INSERT INTO trunc_stats_test2 DEFAULT VALUES;
+RELEASE SAVEPOINT p1;
+COMMIT;
+-- rollback a savepoint: this should count 4 inserts and have 2
+-- live tuples after commit (and 2 dead ones due to aborted subxact)
+BEGIN;
+INSERT INTO trunc_stats_test3 DEFAULT VALUES;
+INSERT INTO trunc_stats_test3 DEFAULT VALUES;
+SAVEPOINT p1;
+INSERT INTO trunc_stats_test3 DEFAULT VALUES;
+INSERT INTO trunc_stats_test3 DEFAULT VALUES;
+TRUNCATE trunc_stats_test3;
+INSERT INTO trunc_stats_test3 DEFAULT VALUES;
+ROLLBACK TO SAVEPOINT p1;
+COMMIT;
+-- rollback a truncate: this should count 2 inserts and produce 2 dead tuples
+BEGIN;
+INSERT INTO trunc_stats_test4 DEFAULT VALUES;
+INSERT INTO trunc_stats_test4 DEFAULT VALUES;
+TRUNCATE trunc_stats_test4;
+INSERT INTO trunc_stats_test4 DEFAULT VALUES;
+ROLLBACK;
+-- do a seqscan
+SELECT count(*) FROM tenk2;
+ count 
+-------
+ 10000
+(1 row)
+
+-- do an indexscan
+-- make sure it is not a bitmap scan, which might skip fetching heap tuples
+SET enable_bitmapscan TO off;
+SELECT count(*) FROM tenk2 WHERE unique1 = 1;
+ count 
+-------
+     1
+(1 row)
+
+RESET enable_bitmapscan;
+-- ensure pending stats are flushed
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+-- check effects
+BEGIN;
+SET LOCAL stats_fetch_consistency = snapshot;
+SELECT relname, n_tup_ins, n_tup_upd, n_tup_del, n_live_tup, n_dead_tup
+  FROM pg_stat_user_tables
+ WHERE relname like 'trunc_stats_test%' order by relname;
+      relname      | n_tup_ins | n_tup_upd | n_tup_del | n_live_tup | n_dead_tup 
+-------------------+-----------+-----------+-----------+------------+------------
+ trunc_stats_test  |         3 |         0 |         0 |          0 |          0
+ trunc_stats_test1 |         4 |         2 |         1 |          1 |          0
+ trunc_stats_test2 |         1 |         0 |         0 |          1 |          0
+ trunc_stats_test3 |         4 |         0 |         0 |          2 |          2
+ trunc_stats_test4 |         2 |         0 |         0 |          0 |          2
+(5 rows)
+
+SELECT st.seq_scan >= pr.seq_scan + 1,
+       st.seq_tup_read >= pr.seq_tup_read + cl.reltuples,
+       st.idx_scan >= pr.idx_scan + 1,
+       st.idx_tup_fetch >= pr.idx_tup_fetch + 1
+  FROM pg_stat_user_tables AS st, pg_class AS cl, prevstats AS pr
+ WHERE st.relname='tenk2' AND cl.relname='tenk2';
+ ?column? | ?column? | ?column? | ?column? 
+----------+----------+----------+----------
+ t        | t        | t        | t
+(1 row)
+
+SELECT st.heap_blks_read + st.heap_blks_hit >= pr.heap_blks + cl.relpages,
+       st.idx_blks_read + st.idx_blks_hit >= pr.idx_blks + 1
+  FROM pg_statio_user_tables AS st, pg_class AS cl, prevstats AS pr
+ WHERE st.relname='tenk2' AND cl.relname='tenk2';
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+SELECT pr.snap_ts < pg_stat_get_snapshot_timestamp() as snapshot_newer
+FROM prevstats AS pr;
+ snapshot_newer 
+----------------
+ t
+(1 row)
+
+COMMIT;
+----
+-- Basic tests for track_functions
+---
+CREATE FUNCTION stats_test_func1() RETURNS VOID LANGUAGE plpgsql AS $$BEGIN END;$$;
+SELECT 'stats_test_func1()'::regprocedure::oid AS stats_test_func1_oid \gset
+CREATE FUNCTION stats_test_func2() RETURNS VOID LANGUAGE plpgsql AS $$BEGIN END;$$;
+SELECT 'stats_test_func2()'::regprocedure::oid AS stats_test_func2_oid \gset
+-- test that stats are accumulated
+BEGIN;
+SET LOCAL stats_fetch_consistency = none;
+SELECT pg_stat_get_function_calls(:stats_test_func1_oid);
+ pg_stat_get_function_calls 
+----------------------------
+                           
+(1 row)
+
+SELECT pg_stat_get_xact_function_calls(:stats_test_func1_oid);
+ pg_stat_get_xact_function_calls 
+---------------------------------
+                                
+(1 row)
+
+SELECT stats_test_func1();
+ stats_test_func1 
+------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_xact_function_calls(:stats_test_func1_oid);
+ pg_stat_get_xact_function_calls 
+---------------------------------
+                               1
+(1 row)
+
+SELECT stats_test_func1();
+ stats_test_func1 
+------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_xact_function_calls(:stats_test_func1_oid);
+ pg_stat_get_xact_function_calls 
+---------------------------------
+                               2
+(1 row)
+
+SELECT pg_stat_get_function_calls(:stats_test_func1_oid);
+ pg_stat_get_function_calls 
+----------------------------
+                          0
+(1 row)
+
+COMMIT;
+-- Verify that function stats are not transactional
+-- rolled back savepoint in committing transaction
+BEGIN;
+SELECT stats_test_func2();
+ stats_test_func2 
+------------------
+ 
+(1 row)
+
+SAVEPOINT foo;
+SELECT stats_test_func2();
+ stats_test_func2 
+------------------
+ 
+(1 row)
+
+ROLLBACK TO SAVEPOINT foo;
+SELECT pg_stat_get_xact_function_calls(:stats_test_func2_oid);
+ pg_stat_get_xact_function_calls 
+---------------------------------
+                               2
+(1 row)
+
+SELECT stats_test_func2();
+ stats_test_func2 
+------------------
+ 
+(1 row)
+
+COMMIT;
+-- rolled back transaction
+BEGIN;
+SELECT stats_test_func2();
+ stats_test_func2 
+------------------
+ 
+(1 row)
+
+ROLLBACK;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+-- check collected stats
+SELECT funcname, calls FROM pg_stat_user_functions WHERE funcid = :stats_test_func1_oid;
+     funcname     | calls 
+------------------+-------
+ stats_test_func1 |     2
+(1 row)
+
+SELECT funcname, calls FROM pg_stat_user_functions WHERE funcid = :stats_test_func2_oid;
+     funcname     | calls 
+------------------+-------
+ stats_test_func2 |     4
+(1 row)
+
+-- check that a rolled back drop function stats leaves stats alive
+BEGIN;
+SELECT funcname, calls FROM pg_stat_user_functions WHERE funcid = :stats_test_func1_oid;
+     funcname     | calls 
+------------------+-------
+ stats_test_func1 |     2
+(1 row)
+
+DROP FUNCTION stats_test_func1();
+-- shouldn't be visible via view
+SELECT funcname, calls FROM pg_stat_user_functions WHERE funcid = :stats_test_func1_oid;
+ funcname | calls 
+----------+-------
+(0 rows)
+
+-- but still via oid access
+SELECT pg_stat_get_function_calls(:stats_test_func1_oid);
+ pg_stat_get_function_calls 
+----------------------------
+                          2
+(1 row)
+
+ROLLBACK;
+SELECT funcname, calls FROM pg_stat_user_functions WHERE funcid = :stats_test_func1_oid;
+     funcname     | calls 
+------------------+-------
+ stats_test_func1 |     2
+(1 row)
+
+SELECT pg_stat_get_function_calls(:stats_test_func1_oid);
+ pg_stat_get_function_calls 
+----------------------------
+                          2
+(1 row)
+
+-- check that function dropped in main transaction leaves no stats behind
+BEGIN;
+DROP FUNCTION stats_test_func1();
+COMMIT;
+SELECT funcname, calls FROM pg_stat_user_functions WHERE funcid = :stats_test_func1_oid;
+ funcname | calls 
+----------+-------
+(0 rows)
+
+SELECT pg_stat_get_function_calls(:stats_test_func1_oid);
+ pg_stat_get_function_calls 
+----------------------------
+                           
+(1 row)
+
+-- check that function dropped in a subtransaction leaves no stats behind
+BEGIN;
+SELECT stats_test_func2();
+ stats_test_func2 
+------------------
+ 
+(1 row)
+
+SAVEPOINT a;
+SELECT stats_test_func2();
+ stats_test_func2 
+------------------
+ 
+(1 row)
+
+SAVEPOINT b;
+DROP FUNCTION stats_test_func2();
+COMMIT;
+SELECT funcname, calls FROM pg_stat_user_functions WHERE funcid = :stats_test_func2_oid;
+ funcname | calls 
+----------+-------
+(0 rows)
+
+SELECT pg_stat_get_function_calls(:stats_test_func2_oid);
+ pg_stat_get_function_calls 
+----------------------------
+                           
+(1 row)
+
+-- Check that stats for relations are dropped. For that we need to access stats
+-- by oid after the DROP TABLE. Save oids.
+CREATE TABLE drop_stats_test();
+INSERT INTO drop_stats_test DEFAULT VALUES;
+SELECT 'drop_stats_test'::regclass::oid AS drop_stats_test_oid \gset
+CREATE TABLE drop_stats_test_xact();
+INSERT INTO drop_stats_test_xact DEFAULT VALUES;
+SELECT 'drop_stats_test_xact'::regclass::oid AS drop_stats_test_xact_oid \gset
+CREATE TABLE drop_stats_test_subxact();
+INSERT INTO drop_stats_test_subxact DEFAULT VALUES;
+SELECT 'drop_stats_test_subxact'::regclass::oid AS drop_stats_test_subxact_oid \gset
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_live_tuples(:drop_stats_test_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       1
+(1 row)
+
+DROP TABLE drop_stats_test;
+SELECT pg_stat_get_live_tuples(:drop_stats_test_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       0
+(1 row)
+
+SELECT pg_stat_get_xact_tuples_inserted(:drop_stats_test_oid);
+ pg_stat_get_xact_tuples_inserted 
+----------------------------------
+                                0
+(1 row)
+
+-- check that rollback protects against having stats dropped and that local
+-- modifications don't pose a problem
+SELECT pg_stat_get_live_tuples(:drop_stats_test_xact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       1
+(1 row)
+
+SELECT pg_stat_get_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_tuples_inserted 
+-----------------------------
+                           1
+(1 row)
+
+SELECT pg_stat_get_xact_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_xact_tuples_inserted 
+----------------------------------
+                                0
+(1 row)
+
+BEGIN;
+INSERT INTO drop_stats_test_xact DEFAULT VALUES;
+SELECT pg_stat_get_xact_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_xact_tuples_inserted 
+----------------------------------
+                                1
+(1 row)
+
+DROP TABLE drop_stats_test_xact;
+SELECT pg_stat_get_xact_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_xact_tuples_inserted 
+----------------------------------
+                                0
+(1 row)
+
+ROLLBACK;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_live_tuples(:drop_stats_test_xact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       1
+(1 row)
+
+SELECT pg_stat_get_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_tuples_inserted 
+-----------------------------
+                           2
+(1 row)
+
+-- transactional drop
+SELECT pg_stat_get_live_tuples(:drop_stats_test_xact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       1
+(1 row)
+
+SELECT pg_stat_get_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_tuples_inserted 
+-----------------------------
+                           2
+(1 row)
+
+BEGIN;
+INSERT INTO drop_stats_test_xact DEFAULT VALUES;
+SELECT pg_stat_get_xact_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_xact_tuples_inserted 
+----------------------------------
+                                1
+(1 row)
+
+DROP TABLE drop_stats_test_xact;
+SELECT pg_stat_get_xact_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_xact_tuples_inserted 
+----------------------------------
+                                0
+(1 row)
+
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_live_tuples(:drop_stats_test_xact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       0
+(1 row)
+
+SELECT pg_stat_get_tuples_inserted(:drop_stats_test_xact_oid);
+ pg_stat_get_tuples_inserted 
+-----------------------------
+                           0
+(1 row)
+
+-- savepoint rollback (2 levels)
+SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       1
+(1 row)
+
+BEGIN;
+INSERT INTO drop_stats_test_subxact DEFAULT VALUES;
+SAVEPOINT sp1;
+INSERT INTO drop_stats_test_subxact DEFAULT VALUES;
+SELECT pg_stat_get_xact_tuples_inserted(:drop_stats_test_subxact_oid);
+ pg_stat_get_xact_tuples_inserted 
+----------------------------------
+                                2
+(1 row)
+
+SAVEPOINT sp2;
+DROP TABLE drop_stats_test_subxact;
+ROLLBACK TO SAVEPOINT sp2;
+SELECT pg_stat_get_xact_tuples_inserted(:drop_stats_test_subxact_oid);
+ pg_stat_get_xact_tuples_inserted 
+----------------------------------
+                                2
+(1 row)
+
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       3
+(1 row)
+
+-- savepoint rolback (1 level)
+SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       3
+(1 row)
+
+BEGIN;
+SAVEPOINT sp1;
+DROP TABLE drop_stats_test_subxact;
+SAVEPOINT sp2;
+ROLLBACK TO SAVEPOINT sp1;
+COMMIT;
+SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       3
+(1 row)
+
+-- and now actually drop
+SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       3
+(1 row)
+
+BEGIN;
+SAVEPOINT sp1;
+DROP TABLE drop_stats_test_subxact;
+SAVEPOINT sp2;
+RELEASE SAVEPOINT sp1;
+COMMIT;
+SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid);
+ pg_stat_get_live_tuples 
+-------------------------
+                       0
+(1 row)
+
+DROP TABLE trunc_stats_test, trunc_stats_test1, trunc_stats_test2, trunc_stats_test3, trunc_stats_test4;
+DROP TABLE prevstats;
+-----
+-- Test that last_seq_scan, last_idx_scan are correctly maintained
+--
+-- Perform test using a temporary table. That way autovacuum etc won't
+-- interfere. To be able to check that timestamps increase, we sleep for 100ms
+-- between tests, assuming that there aren't systems with a coarser timestamp
+-- granularity.
+-----
+BEGIN;
+CREATE TEMPORARY TABLE test_last_scan(idx_col int primary key, noidx_col int);
+INSERT INTO test_last_scan(idx_col, noidx_col) VALUES(1, 1);
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT last_seq_scan, last_idx_scan FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass;
+ last_seq_scan | last_idx_scan 
+---------------+---------------
+               | 
+(1 row)
+
+COMMIT;
+SELECT stats_reset IS NOT NULL AS has_stats_reset
+  FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass;
+ has_stats_reset 
+-----------------
+ f
+(1 row)
+
+SELECT pg_stat_reset_single_table_counters('test_last_scan'::regclass);
+ pg_stat_reset_single_table_counters 
+-------------------------------------
+ 
+(1 row)
+
+SELECT seq_scan, idx_scan, stats_reset IS NOT NULL AS has_stats_reset
+  FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass;
+ seq_scan | idx_scan | has_stats_reset 
+----------+----------+-----------------
+        0 |        0 | t
+(1 row)
+
+-- ensure we start out with exactly one index and sequential scan
+BEGIN;
+SET LOCAL enable_seqscan TO on;
+SET LOCAL enable_indexscan TO on;
+SET LOCAL enable_bitmapscan TO off;
+EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE noidx_col = 1;
+            QUERY PLAN            
+----------------------------------
+ Aggregate
+   ->  Seq Scan on test_last_scan
+         Filter: (noidx_col = 1)
+(3 rows)
+
+SELECT count(*) FROM test_last_scan WHERE noidx_col = 1;
+ count 
+-------
+     1
+(1 row)
+
+SET LOCAL enable_seqscan TO off;
+EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1;
+                          QUERY PLAN                          
+--------------------------------------------------------------
+ Aggregate
+   ->  Index Scan using test_last_scan_pkey on test_last_scan
+         Index Cond: (idx_col = 1)
+(3 rows)
+
+SELECT count(*) FROM test_last_scan WHERE idx_col = 1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+COMMIT;
+-- fetch timestamps from before the next test
+SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx
+FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset
+SELECT pg_sleep(0.1); -- assume a minimum timestamp granularity of 100ms
+ pg_sleep 
+----------
+ 
+(1 row)
+
+-- cause one sequential scan
+BEGIN;
+SET LOCAL enable_seqscan TO on;
+SET LOCAL enable_indexscan TO off;
+SET LOCAL enable_bitmapscan TO off;
+EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE noidx_col = 1;
+            QUERY PLAN            
+----------------------------------
+ Aggregate
+   ->  Seq Scan on test_last_scan
+         Filter: (noidx_col = 1)
+(3 rows)
+
+SELECT count(*) FROM test_last_scan WHERE noidx_col = 1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+COMMIT;
+-- check that just sequential scan stats were incremented
+SELECT seq_scan, :'test_last_seq' < last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' = last_idx_scan AS idx_ok
+FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass;
+ seq_scan | seq_ok | idx_scan | idx_ok 
+----------+--------+----------+--------
+        2 | t      |        1 | t
+(1 row)
+
+-- fetch timestamps from before the next test
+SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx
+FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset
+SELECT pg_sleep(0.1);
+ pg_sleep 
+----------
+ 
+(1 row)
+
+-- cause one index scan
+BEGIN;
+SET LOCAL enable_seqscan TO off;
+SET LOCAL enable_indexscan TO on;
+SET LOCAL enable_bitmapscan TO off;
+EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1;
+                          QUERY PLAN                          
+--------------------------------------------------------------
+ Aggregate
+   ->  Index Scan using test_last_scan_pkey on test_last_scan
+         Index Cond: (idx_col = 1)
+(3 rows)
+
+SELECT count(*) FROM test_last_scan WHERE idx_col = 1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+COMMIT;
+-- check that just index scan stats were incremented
+SELECT seq_scan, :'test_last_seq' = last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' < last_idx_scan AS idx_ok
+FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass;
+ seq_scan | seq_ok | idx_scan | idx_ok 
+----------+--------+----------+--------
+        2 | t      |        2 | t
+(1 row)
+
+-- fetch timestamps from before the next test
+SELECT last_seq_scan AS test_last_seq, last_idx_scan AS test_last_idx
+FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass \gset
+SELECT pg_sleep(0.1);
+ pg_sleep 
+----------
+ 
+(1 row)
+
+-- cause one bitmap index scan
+BEGIN;
+SET LOCAL enable_seqscan TO off;
+SET LOCAL enable_indexscan TO off;
+SET LOCAL enable_bitmapscan TO on;
+EXPLAIN (COSTS off) SELECT count(*) FROM test_last_scan WHERE idx_col = 1;
+                      QUERY PLAN                      
+------------------------------------------------------
+ Aggregate
+   ->  Bitmap Heap Scan on test_last_scan
+         Recheck Cond: (idx_col = 1)
+         ->  Bitmap Index Scan on test_last_scan_pkey
+               Index Cond: (idx_col = 1)
+(5 rows)
+
+SELECT count(*) FROM test_last_scan WHERE idx_col = 1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+COMMIT;
+-- check that just index scan stats were incremented
+SELECT seq_scan, :'test_last_seq' = last_seq_scan AS seq_ok, idx_scan, :'test_last_idx' < last_idx_scan AS idx_ok
+FROM pg_stat_all_tables WHERE relid = 'test_last_scan'::regclass;
+ seq_scan | seq_ok | idx_scan | idx_ok 
+----------+--------+----------+--------
+        2 | t      |        3 | t
+(1 row)
+
+-- check the stats in pg_stat_all_indexes
+SELECT idx_scan, :'test_last_idx' < last_idx_scan AS idx_ok,
+  stats_reset IS NOT NULL AS has_stats_reset
+  FROM pg_stat_all_indexes WHERE indexrelid = 'test_last_scan_pkey'::regclass;
+ idx_scan | idx_ok | has_stats_reset 
+----------+--------+-----------------
+        3 | t      | f
+(1 row)
+
+-- check that the stats in pg_stat_all_indexes are reset
+SELECT pg_stat_reset_single_table_counters('test_last_scan_pkey'::regclass);
+ pg_stat_reset_single_table_counters 
+-------------------------------------
+ 
+(1 row)
+
+SELECT idx_scan, stats_reset IS NOT NULL AS has_stats_reset
+  FROM pg_stat_all_indexes WHERE indexrelid = 'test_last_scan_pkey'::regclass;
+ idx_scan | has_stats_reset 
+----------+-----------------
+        0 | t
+(1 row)
+
+-----
+-- Test reset of some stats for shared table
+-----
+-- This updates the comment of the database currently in use in
+-- pg_shdescription with a fake value, then sets it back to its
+-- original value.
+SELECT shobj_description(d.oid, 'pg_database') as description_before
+  FROM pg_database d WHERE datname = current_database() \gset
+-- force some stats in pg_shdescription.
+BEGIN;
+SELECT current_database() as datname \gset
+COMMENT ON DATABASE :"datname" IS 'This is a test comment';
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+COMMIT;
+-- check that the stats are reset.
+SELECT (n_tup_ins + n_tup_upd) > 0 AS has_data FROM pg_stat_all_tables
+  WHERE relid = 'pg_shdescription'::regclass;
+ has_data 
+----------
+ t
+(1 row)
+
+SELECT pg_stat_reset_single_table_counters('pg_shdescription'::regclass);
+ pg_stat_reset_single_table_counters 
+-------------------------------------
+ 
+(1 row)
+
+SELECT (n_tup_ins + n_tup_upd) > 0 AS has_data FROM pg_stat_all_tables
+  WHERE relid = 'pg_shdescription'::regclass;
+ has_data 
+----------
+ f
+(1 row)
+
+-- set back comment
+\if :{?description_before}
+  COMMENT ON DATABASE :"datname" IS :'description_before';
+\else
+  COMMENT ON DATABASE :"datname" IS NULL;
+\endif
+-----
+-- Test that various stats views are being properly populated
+-----
+-- Test that sessions is incremented when a new session is started in pg_stat_database
+SELECT sessions AS db_stat_sessions FROM pg_stat_database WHERE datname = (SELECT current_database()) \gset
+\c
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT sessions > :db_stat_sessions FROM pg_stat_database WHERE datname = (SELECT current_database());
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test pg_stat_checkpointer checkpointer-related stats, together with pg_stat_wal
+SELECT num_requested AS rqst_ckpts_before FROM pg_stat_checkpointer \gset
+-- Test pg_stat_wal
+SELECT wal_bytes AS wal_bytes_before FROM pg_stat_wal \gset
+-- Test pg_stat_get_backend_wal()
+SELECT wal_bytes AS backend_wal_bytes_before from pg_stat_get_backend_wal(pg_backend_pid()) \gset
+-- Make a temp table so our temp schema exists
+CREATE TEMP TABLE test_stats_temp AS SELECT 17;
+DROP TABLE test_stats_temp;
+-- Checkpoint twice: The checkpointer reports stats after reporting completion
+-- of the checkpoint. But after a second checkpoint we'll see at least the
+-- results of the first.
+--
+-- While at it, test checkpoint options.  Note that we don't test MODE SPREAD
+-- because it would prolong the test.
+CHECKPOINT (WRONG);
+ERROR:  unrecognized CHECKPOINT option "wrong"
+LINE 1: CHECKPOINT (WRONG);
+                    ^
+CHECKPOINT (MODE WRONG);
+ERROR:  unrecognized MODE option "wrong"
+LINE 1: CHECKPOINT (MODE WRONG);
+                    ^
+CHECKPOINT (MODE FAST, FLUSH_UNLOGGED FALSE);
+CHECKPOINT (FLUSH_UNLOGGED);
+SELECT num_requested > :rqst_ckpts_before FROM pg_stat_checkpointer;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT wal_bytes > :wal_bytes_before FROM pg_stat_wal;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT wal_bytes > :backend_wal_bytes_before FROM pg_stat_get_backend_wal(pg_backend_pid());
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test pg_stat_get_backend_idset() and some allied functions.
+-- In particular, verify that their notion of backend ID matches
+-- our temp schema index.
+SELECT (current_schemas(true))[1] = ('pg_temp_' || beid::text) AS match
+FROM pg_stat_get_backend_idset() beid
+WHERE pg_stat_get_backend_pid(beid) = pg_backend_pid();
+ match 
+-------
+ t
+(1 row)
+
+-----
+-- Test that resetting stats works for reset timestamp
+-----
+-- Test that reset_slru with a specified SLRU works.
+SELECT stats_reset AS slru_commit_ts_reset_ts FROM pg_stat_slru WHERE name = 'commit_timestamp' \gset
+SELECT stats_reset AS slru_notify_reset_ts FROM pg_stat_slru WHERE name = 'notify' \gset
+SELECT pg_stat_reset_slru('commit_timestamp');
+ pg_stat_reset_slru 
+--------------------
+ 
+(1 row)
+
+SELECT stats_reset > :'slru_commit_ts_reset_ts'::timestamptz FROM pg_stat_slru WHERE name = 'commit_timestamp';
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT stats_reset AS slru_commit_ts_reset_ts FROM pg_stat_slru WHERE name = 'commit_timestamp' \gset
+-- Test that multiple SLRUs are reset when no specific SLRU provided to reset function
+SELECT pg_stat_reset_slru();
+ pg_stat_reset_slru 
+--------------------
+ 
+(1 row)
+
+SELECT stats_reset > :'slru_commit_ts_reset_ts'::timestamptz FROM pg_stat_slru WHERE name = 'commit_timestamp';
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT stats_reset > :'slru_notify_reset_ts'::timestamptz FROM pg_stat_slru WHERE name = 'notify';
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test that reset_shared with archiver specified as the stats type works
+SELECT stats_reset AS archiver_reset_ts FROM pg_stat_archiver \gset
+SELECT pg_stat_reset_shared('archiver');
+ pg_stat_reset_shared 
+----------------------
+ 
+(1 row)
+
+SELECT stats_reset > :'archiver_reset_ts'::timestamptz FROM pg_stat_archiver;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test that reset_shared with bgwriter specified as the stats type works
+SELECT stats_reset AS bgwriter_reset_ts FROM pg_stat_bgwriter \gset
+SELECT pg_stat_reset_shared('bgwriter');
+ pg_stat_reset_shared 
+----------------------
+ 
+(1 row)
+
+SELECT stats_reset > :'bgwriter_reset_ts'::timestamptz FROM pg_stat_bgwriter;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test that reset_shared with checkpointer specified as the stats type works
+SELECT stats_reset AS checkpointer_reset_ts FROM pg_stat_checkpointer \gset
+SELECT pg_stat_reset_shared('checkpointer');
+ pg_stat_reset_shared 
+----------------------
+ 
+(1 row)
+
+SELECT stats_reset > :'checkpointer_reset_ts'::timestamptz FROM pg_stat_checkpointer;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test that reset_shared with recovery_prefetch specified as the stats type works
+SELECT stats_reset AS recovery_prefetch_reset_ts FROM pg_stat_recovery_prefetch \gset
+SELECT pg_stat_reset_shared('recovery_prefetch');
+ pg_stat_reset_shared 
+----------------------
+ 
+(1 row)
+
+SELECT stats_reset > :'recovery_prefetch_reset_ts'::timestamptz FROM pg_stat_recovery_prefetch;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test that reset_shared with slru specified as the stats type works
+SELECT max(stats_reset) AS slru_reset_ts FROM pg_stat_slru \gset
+SELECT pg_stat_reset_shared('slru');
+ pg_stat_reset_shared 
+----------------------
+ 
+(1 row)
+
+SELECT max(stats_reset) > :'slru_reset_ts'::timestamptz FROM pg_stat_slru;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test that reset_shared with wal specified as the stats type works
+SELECT stats_reset AS wal_reset_ts FROM pg_stat_wal \gset
+SELECT pg_stat_reset_shared('wal');
+ pg_stat_reset_shared 
+----------------------
+ 
+(1 row)
+
+SELECT stats_reset > :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test error case for reset_shared with unknown stats type
+SELECT pg_stat_reset_shared('unknown');
+ERROR:  unrecognized reset target: "unknown"
+HINT:  Target must be "archiver", "bgwriter", "checkpointer", "io", "recovery_prefetch", "slru", or "wal".
+-- Test that reset works for pg_stat_database
+-- Since pg_stat_database stats_reset starts out as NULL, reset it once first so we have something to compare it to
+SELECT pg_stat_reset();
+ pg_stat_reset 
+---------------
+ 
+(1 row)
+
+SELECT stats_reset AS db_reset_ts FROM pg_stat_database WHERE datname = (SELECT current_database()) \gset
+SELECT pg_stat_reset();
+ pg_stat_reset 
+---------------
+ 
+(1 row)
+
+SELECT stats_reset > :'db_reset_ts'::timestamptz FROM pg_stat_database WHERE datname = (SELECT current_database());
+ ?column? 
+----------
+ t
+(1 row)
+
+----
+-- pg_stat_get_snapshot_timestamp behavior
+----
+BEGIN;
+SET LOCAL stats_fetch_consistency = snapshot;
+-- no snapshot yet, return NULL
+SELECT pg_stat_get_snapshot_timestamp();
+ pg_stat_get_snapshot_timestamp 
+--------------------------------
+ 
+(1 row)
+
+-- any attempt at accessing stats will build snapshot
+SELECT pg_stat_get_function_calls(0);
+ pg_stat_get_function_calls 
+----------------------------
+                           
+(1 row)
+
+SELECT pg_stat_get_snapshot_timestamp() >= NOW();
+ ?column? 
+----------
+ t
+(1 row)
+
+-- shows NULL again after clearing
+SELECT pg_stat_clear_snapshot();
+ pg_stat_clear_snapshot 
+------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_snapshot_timestamp();
+ pg_stat_get_snapshot_timestamp 
+--------------------------------
+ 
+(1 row)
+
+COMMIT;
+----
+-- Changing stats_fetch_consistency in a transaction.
+----
+BEGIN;
+-- Stats filled under the cache mode
+SET LOCAL stats_fetch_consistency = cache;
+SELECT pg_stat_get_function_calls(0);
+ pg_stat_get_function_calls 
+----------------------------
+                           
+(1 row)
+
+SELECT pg_stat_get_snapshot_timestamp() IS NOT NULL AS snapshot_ok;
+ snapshot_ok 
+-------------
+ f
+(1 row)
+
+-- Success in accessing pre-existing snapshot data.
+SET LOCAL stats_fetch_consistency = snapshot;
+SELECT pg_stat_get_snapshot_timestamp() IS NOT NULL AS snapshot_ok;
+ snapshot_ok 
+-------------
+ f
+(1 row)
+
+SELECT pg_stat_get_function_calls(0);
+ pg_stat_get_function_calls 
+----------------------------
+                           
+(1 row)
+
+SELECT pg_stat_get_snapshot_timestamp() IS NOT NULL AS snapshot_ok;
+ snapshot_ok 
+-------------
+ t
+(1 row)
+
+-- Snapshot cleared.
+SET LOCAL stats_fetch_consistency = none;
+SELECT pg_stat_get_snapshot_timestamp() IS NOT NULL AS snapshot_ok;
+ snapshot_ok 
+-------------
+ f
+(1 row)
+
+SELECT pg_stat_get_function_calls(0);
+ pg_stat_get_function_calls 
+----------------------------
+                           
+(1 row)
+
+SELECT pg_stat_get_snapshot_timestamp() IS NOT NULL AS snapshot_ok;
+ snapshot_ok 
+-------------
+ f
+(1 row)
+
+ROLLBACK;
+----
+-- pg_stat_have_stats behavior
+----
+-- fixed-numbered stats exist
+SELECT pg_stat_have_stats('bgwriter', 0, 0);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+-- unknown stats kinds error out
+SELECT pg_stat_have_stats('zaphod', 0, 0);
+ERROR:  invalid statistics kind: "zaphod"
+-- db stats have objid 0
+SELECT pg_stat_have_stats('database', :dboid, 1);
+ pg_stat_have_stats 
+--------------------
+ f
+(1 row)
+
+SELECT pg_stat_have_stats('database', :dboid, 0);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+-- pg_stat_have_stats returns true for committed index creation
+CREATE table stats_test_tab1 as select generate_series(1,10) a;
+CREATE index stats_test_idx1 on stats_test_tab1(a);
+SELECT 'stats_test_idx1'::regclass::oid AS stats_test_idx1_oid \gset
+SET enable_seqscan TO off;
+select a from stats_test_tab1 where a = 3;
+ a 
+---
+ 3
+(1 row)
+
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+-- pg_stat_have_stats returns false for dropped index with stats
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+DROP index stats_test_idx1;
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ f
+(1 row)
+
+-- pg_stat_have_stats returns false for rolled back index creation
+BEGIN;
+CREATE index stats_test_idx1 on stats_test_tab1(a);
+SELECT 'stats_test_idx1'::regclass::oid AS stats_test_idx1_oid \gset
+select a from stats_test_tab1 where a = 3;
+ a 
+---
+ 3
+(1 row)
+
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+ROLLBACK;
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ f
+(1 row)
+
+-- pg_stat_have_stats returns true for reindex CONCURRENTLY
+CREATE index stats_test_idx1 on stats_test_tab1(a);
+SELECT 'stats_test_idx1'::regclass::oid AS stats_test_idx1_oid \gset
+select a from stats_test_tab1 where a = 3;
+ a 
+---
+ 3
+(1 row)
+
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+REINDEX index CONCURRENTLY stats_test_idx1;
+-- false for previous oid
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ f
+(1 row)
+
+-- true for new oid
+SELECT 'stats_test_idx1'::regclass::oid AS stats_test_idx1_oid \gset
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+-- pg_stat_have_stats returns true for a rolled back drop index with stats
+BEGIN;
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+DROP index stats_test_idx1;
+ROLLBACK;
+SELECT pg_stat_have_stats('relation', :dboid, :stats_test_idx1_oid);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+-- put enable_seqscan back to on
+SET enable_seqscan TO on;
+-- ensure that stats accessors handle NULL input correctly
+SELECT pg_stat_get_replication_slot(NULL);
+ pg_stat_get_replication_slot 
+------------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_subscription_stats(NULL);
+ pg_stat_get_subscription_stats 
+--------------------------------
+ 
+(1 row)
+
+-- Test that the following operations are tracked in pg_stat_io and in
+-- backend stats:
+-- - reads of target blocks into shared buffers
+-- - writes of shared buffers to permanent storage
+-- - extends of relations using shared buffers
+-- - fsyncs done to ensure the durability of data dirtying shared buffers
+-- - shared buffer hits
+-- - WAL writes and fsyncs in IOContext IOCONTEXT_NORMAL
+-- There is no test for blocks evicted from shared buffers, because we cannot
+-- be sure of the state of shared buffers at the point the test is run.
+-- Create a regular table and insert some data to generate IOCONTEXT_NORMAL
+-- extends.
+SELECT pid AS checkpointer_pid FROM pg_stat_activity
+  WHERE backend_type = 'checkpointer' \gset
+SELECT sum(extends) AS io_sum_shared_before_extends
+  FROM pg_stat_io WHERE context = 'normal' AND object = 'relation' \gset
+SELECT sum(extends) AS my_io_sum_shared_before_extends
+  FROM pg_stat_get_backend_io(pg_backend_pid())
+  WHERE context = 'normal' AND object = 'relation' \gset
+SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
+  FROM pg_stat_io
+  WHERE object = 'relation' \gset io_sum_shared_before_
+SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
+  FROM pg_stat_get_backend_io(pg_backend_pid())
+  WHERE object = 'relation' \gset my_io_sum_shared_before_
+SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
+  FROM pg_stat_io
+  WHERE context = 'normal' AND object = 'wal' \gset io_sum_wal_normal_before_
+CREATE TABLE test_io_shared(a int);
+INSERT INTO test_io_shared SELECT i FROM generate_series(1,100)i;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT sum(extends) AS io_sum_shared_after_extends
+  FROM pg_stat_io WHERE context = 'normal' AND object = 'relation' \gset
+SELECT :io_sum_shared_after_extends > :io_sum_shared_before_extends;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT sum(extends) AS my_io_sum_shared_after_extends
+  FROM pg_stat_get_backend_io(pg_backend_pid())
+  WHERE context = 'normal' AND object = 'relation' \gset
+SELECT :my_io_sum_shared_after_extends > :my_io_sum_shared_before_extends;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- After a checkpoint, there should be some additional IOCONTEXT_NORMAL writes
+-- and fsyncs in the global stats (usually not for the backend).
+-- See comment above for rationale for two explicit CHECKPOINTs.
+CHECKPOINT;
+CHECKPOINT;
+SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
+  FROM pg_stat_io
+  WHERE object = 'relation' \gset io_sum_shared_after_
+SELECT :io_sum_shared_after_writes > :io_sum_shared_before_writes;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT current_setting('fsync') = 'off'
+  OR :io_sum_shared_after_fsyncs > :io_sum_shared_before_fsyncs;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
+  FROM pg_stat_get_backend_io(pg_backend_pid())
+  WHERE object = 'relation' \gset my_io_sum_shared_after_
+SELECT :my_io_sum_shared_after_writes >= :my_io_sum_shared_before_writes;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT current_setting('fsync') = 'off'
+  OR :my_io_sum_shared_after_fsyncs >= :my_io_sum_shared_before_fsyncs;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT sum(writes) AS writes, sum(fsyncs) AS fsyncs
+  FROM pg_stat_io
+  WHERE context = 'normal' AND object = 'wal' \gset io_sum_wal_normal_after_
+SELECT current_setting('synchronous_commit') = 'on';
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT :io_sum_wal_normal_after_writes > :io_sum_wal_normal_before_writes;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT current_setting('fsync') = 'off'
+  OR current_setting('wal_sync_method') IN ('open_sync', 'open_datasync')
+  OR :io_sum_wal_normal_after_fsyncs > :io_sum_wal_normal_before_fsyncs;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Change the tablespace so that the table is rewritten directly, then SELECT
+-- from it to cause it to be read back into shared buffers.
+SELECT sum(reads) AS io_sum_shared_before_reads
+  FROM pg_stat_io WHERE context = 'normal' AND object = 'relation' \gset
+-- Do this in a transaction to prevent spurious failures due to concurrent accesses to our newly
+-- rewritten table, e.g. by autovacuum.
+BEGIN;
+ALTER TABLE test_io_shared SET TABLESPACE regress_tblspace;
+-- SELECT from the table so that the data is read into shared buffers and
+-- context 'normal', object 'relation' reads are counted.
+SELECT COUNT(*) FROM test_io_shared;
+ count 
+-------
+   100
+(1 row)
+
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT sum(reads) AS io_sum_shared_after_reads
+  FROM pg_stat_io WHERE context = 'normal' AND object = 'relation'  \gset
+SELECT :io_sum_shared_after_reads > :io_sum_shared_before_reads;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT sum(hits) AS io_sum_shared_before_hits
+  FROM pg_stat_io WHERE context = 'normal' AND object = 'relation' \gset
+-- Select from the table again to count hits.
+-- Ensure we generate hits by forcing a nested loop self-join with no
+-- materialize node. The outer side's buffer will stay pinned, preventing its
+-- eviction, while we loop through the inner side and generate hits.
+BEGIN;
+SET LOCAL enable_nestloop TO on; SET LOCAL enable_mergejoin TO off;
+SET LOCAL enable_hashjoin TO off; SET LOCAL enable_material TO off;
+-- ensure plan stays as we expect it to
+EXPLAIN (COSTS OFF) SELECT COUNT(*) FROM test_io_shared t1 INNER JOIN test_io_shared t2 USING (a);
+                QUERY PLAN                 
+-------------------------------------------
+ Aggregate
+   ->  Nested Loop
+         Join Filter: (t1.a = t2.a)
+         ->  Seq Scan on test_io_shared t1
+         ->  Seq Scan on test_io_shared t2
+(5 rows)
+
+SELECT COUNT(*) FROM test_io_shared t1 INNER JOIN test_io_shared t2 USING (a);
+ count 
+-------
+   100
+(1 row)
+
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT sum(hits) AS io_sum_shared_after_hits
+  FROM pg_stat_io WHERE context = 'normal' AND object = 'relation' \gset
+SELECT :io_sum_shared_after_hits > :io_sum_shared_before_hits;
+ ?column? 
+----------
+ t
+(1 row)
+
+DROP TABLE test_io_shared;
+-- Test that the follow IOCONTEXT_LOCAL IOOps are tracked in pg_stat_io:
+-- - eviction of local buffers in order to reuse them
+-- - reads of temporary table blocks into local buffers
+-- - writes of local buffers to permanent storage
+-- - extends of temporary tables
+-- Set temp_buffers to its minimum so that we can trigger writes with fewer
+-- inserted tuples. Do so in a new session in case temporary tables have been
+-- accessed by previous tests in this session.
+\c
+SET temp_buffers TO 100;
+CREATE TEMPORARY TABLE test_io_local(a int, b TEXT);
+SELECT sum(extends) AS extends, sum(evictions) AS evictions, sum(writes) AS writes
+  FROM pg_stat_io
+  WHERE context = 'normal' AND object = 'temp relation' \gset io_sum_local_before_
+-- Insert tuples into the temporary table, generating extends in the stats.
+-- Insert enough values that we need to reuse and write out dirty local
+-- buffers, generating evictions and writes.
+INSERT INTO test_io_local SELECT generate_series(1, 5000) as id, repeat('a', 200);
+-- Ensure the table is large enough to exceed our temp_buffers setting.
+SELECT pg_relation_size('test_io_local') / current_setting('block_size')::int8 > 100;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT sum(reads) AS io_sum_local_before_reads
+  FROM pg_stat_io WHERE context = 'normal' AND object = 'temp relation' \gset
+-- Read in evicted buffers, generating reads.
+SELECT COUNT(*) FROM test_io_local;
+ count 
+-------
+  5000
+(1 row)
+
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT sum(evictions) AS evictions,
+       sum(reads) AS reads,
+       sum(writes) AS writes,
+       sum(extends) AS extends
+  FROM pg_stat_io
+  WHERE context = 'normal' AND object = 'temp relation'  \gset io_sum_local_after_
+SELECT :io_sum_local_after_evictions > :io_sum_local_before_evictions,
+       :io_sum_local_after_reads > :io_sum_local_before_reads,
+       :io_sum_local_after_writes > :io_sum_local_before_writes,
+       :io_sum_local_after_extends > :io_sum_local_before_extends;
+ ?column? | ?column? | ?column? | ?column? 
+----------+----------+----------+----------
+ t        | t        | t        | t
+(1 row)
+
+-- Change the tablespaces so that the temporary table is rewritten to other
+-- local buffers, exercising a different codepath than standard local buffer
+-- writes.
+ALTER TABLE test_io_local SET TABLESPACE regress_tblspace;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT sum(writes) AS io_sum_local_new_tblspc_writes
+  FROM pg_stat_io WHERE context = 'normal' AND object = 'temp relation'  \gset
+SELECT :io_sum_local_new_tblspc_writes > :io_sum_local_after_writes;
+ ?column? 
+----------
+ t
+(1 row)
+
+RESET temp_buffers;
+-- Test that reuse of strategy buffers and reads of blocks into these reused
+-- buffers while VACUUMing are tracked in pg_stat_io. If there is sufficient
+-- demand for shared buffers from concurrent queries, some buffers may be
+-- pinned by other backends before they can be reused. In such cases, the
+-- backend will evict a buffer from outside the ring and add it to the
+-- ring. This is considered an eviction and not a reuse.
+-- Set wal_skip_threshold smaller than the expected size of
+-- test_io_vac_strategy so that, even if wal_level is minimal, VACUUM FULL will
+-- fsync the newly rewritten test_io_vac_strategy instead of writing it to WAL.
+-- Writing it to WAL will result in the newly written relation pages being in
+-- shared buffers -- preventing us from testing BAS_VACUUM BufferAccessStrategy
+-- reads.
+SET wal_skip_threshold = '1 kB';
+SELECT sum(reuses) AS reuses, sum(reads) AS reads, sum(evictions) AS evictions
+  FROM pg_stat_io WHERE context = 'vacuum' \gset io_sum_vac_strategy_before_
+CREATE TABLE test_io_vac_strategy(a int, b int) WITH (autovacuum_enabled = 'false');
+INSERT INTO test_io_vac_strategy SELECT i, i from generate_series(1, 4500)i;
+-- Ensure that the next VACUUM will need to perform IO by rewriting the table
+-- first with VACUUM (FULL).
+VACUUM (FULL) test_io_vac_strategy;
+-- Use the minimum BUFFER_USAGE_LIMIT to cause reuses or evictions with the
+-- smallest table possible.
+VACUUM (PARALLEL 0, BUFFER_USAGE_LIMIT 128) test_io_vac_strategy;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT sum(reuses) AS reuses, sum(reads) AS reads, sum(evictions) AS evictions
+  FROM pg_stat_io WHERE context = 'vacuum' \gset io_sum_vac_strategy_after_
+SELECT :io_sum_vac_strategy_after_reads > :io_sum_vac_strategy_before_reads;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT (:io_sum_vac_strategy_after_reuses + :io_sum_vac_strategy_after_evictions) >
+  (:io_sum_vac_strategy_before_reuses + :io_sum_vac_strategy_before_evictions);
+ ?column? 
+----------
+ t
+(1 row)
+
+RESET wal_skip_threshold;
+-- Test that extends done by a CTAS, which uses a BAS_BULKWRITE
+-- BufferAccessStrategy, are tracked in pg_stat_io.
+SELECT sum(extends) AS io_sum_bulkwrite_strategy_extends_before
+  FROM pg_stat_io WHERE context = 'bulkwrite' \gset
+CREATE TABLE test_io_bulkwrite_strategy AS SELECT i FROM generate_series(1,100)i;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT sum(extends) AS io_sum_bulkwrite_strategy_extends_after
+  FROM pg_stat_io WHERE context = 'bulkwrite' \gset
+SELECT :io_sum_bulkwrite_strategy_extends_after > :io_sum_bulkwrite_strategy_extends_before;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Test IO stats reset
+SELECT pg_stat_have_stats('io', 0, 0);
+ pg_stat_have_stats 
+--------------------
+ t
+(1 row)
+
+SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS io_stats_pre_reset
+  FROM pg_stat_io \gset
+SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_pre_reset
+  FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
+SELECT pg_stat_reset_shared('io');
+ pg_stat_reset_shared 
+----------------------
+ 
+(1 row)
+
+SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS io_stats_post_reset
+  FROM pg_stat_io \gset
+SELECT :io_stats_post_reset < :io_stats_pre_reset;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_post_reset
+  FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
+-- pg_stat_reset_shared() did not reset backend IO stats
+SELECT :my_io_stats_pre_reset <= :my_io_stats_post_reset;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- but pg_stat_reset_backend_stats() does
+SELECT pg_stat_reset_backend_stats(pg_backend_pid());
+ pg_stat_reset_backend_stats 
+-----------------------------
+ 
+(1 row)
+
+SELECT sum(evictions) + sum(reuses) + sum(extends) + sum(fsyncs) + sum(reads) + sum(writes) + sum(writebacks) + sum(hits) AS my_io_stats_post_backend_reset
+  FROM pg_stat_get_backend_io(pg_backend_pid()) \gset
+SELECT :my_io_stats_pre_reset > :my_io_stats_post_backend_reset;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- Check invalid input for pg_stat_get_backend_io()
+SELECT pg_stat_get_backend_io(NULL);
+ pg_stat_get_backend_io 
+------------------------
+(0 rows)
+
+SELECT pg_stat_get_backend_io(0);
+ pg_stat_get_backend_io 
+------------------------
+(0 rows)
+
+-- Auxiliary processes return no data.
+SELECT pg_stat_get_backend_io(:checkpointer_pid);
+ pg_stat_get_backend_io 
+------------------------
+(0 rows)
+
+-- test BRIN index doesn't block HOT update
+CREATE TABLE brin_hot (
+  id  integer PRIMARY KEY,
+  val integer NOT NULL
+) WITH (autovacuum_enabled = off, fillfactor = 70);
+INSERT INTO brin_hot SELECT *, 0 FROM generate_series(1, 235);
+CREATE INDEX val_brin ON brin_hot using brin(val);
+CREATE FUNCTION wait_for_hot_stats() RETURNS void AS $$
+DECLARE
+  start_time timestamptz := clock_timestamp();
+  updated bool;
+BEGIN
+  -- we don't want to wait forever; loop will exit after 30 seconds
+  FOR i IN 1 .. 300 LOOP
+    SELECT (pg_stat_get_tuples_hot_updated('brin_hot'::regclass::oid) > 0) INTO updated;
+    EXIT WHEN updated;
+
+    -- wait a little
+    PERFORM pg_sleep_for('100 milliseconds');
+    -- reset stats snapshot so we can test again
+    PERFORM pg_stat_clear_snapshot();
+  END LOOP;
+  -- report time waited in postmaster log (where it won't change test output)
+  RAISE log 'wait_for_hot_stats delayed % seconds',
+    EXTRACT(epoch FROM clock_timestamp() - start_time);
+END
+$$ LANGUAGE plpgsql;
+UPDATE brin_hot SET val = -3 WHERE id = 42;
+-- We can't just call wait_for_hot_stats() at this point, because we only
+-- transmit stats when the session goes idle, and we probably didn't
+-- transmit the last couple of counts yet thanks to the rate-limiting logic
+-- in pgstat_report_stat().  But instead of waiting for the rate limiter's
+-- timeout to elapse, let's just start a new session.  The old one will
+-- then send its stats before dying.
+\c -
+SELECT wait_for_hot_stats();
+ wait_for_hot_stats 
+--------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_tuples_hot_updated('brin_hot'::regclass::oid);
+ pg_stat_get_tuples_hot_updated 
+--------------------------------
+                              1
+(1 row)
+
+DROP TABLE brin_hot;
+DROP FUNCTION wait_for_hot_stats();
+-- Test handling of index predicates - updating attributes in precicates
+-- should not block HOT when summarizing indexes are involved. We update
+-- a row that was not indexed due to the index predicate, and becomes
+-- indexable - the HOT-updated tuple is forwarded to the BRIN index.
+CREATE TABLE brin_hot_2 (a int, b int);
+INSERT INTO brin_hot_2 VALUES (1, 100);
+CREATE INDEX ON brin_hot_2 USING brin (b) WHERE a = 2;
+UPDATE brin_hot_2 SET a = 2;
+EXPLAIN (COSTS OFF) SELECT * FROM brin_hot_2 WHERE a = 2 AND b = 100;
+            QUERY PLAN             
+-----------------------------------
+ Seq Scan on brin_hot_2
+   Filter: ((a = 2) AND (b = 100))
+(2 rows)
+
+SELECT COUNT(*) FROM brin_hot_2 WHERE a = 2 AND b = 100;
+ count 
+-------
+     1
+(1 row)
+
+SET enable_seqscan = off;
+EXPLAIN (COSTS OFF) SELECT * FROM brin_hot_2 WHERE a = 2 AND b = 100;
+                 QUERY PLAN                  
+---------------------------------------------
+ Bitmap Heap Scan on brin_hot_2
+   Recheck Cond: ((b = 100) AND (a = 2))
+   ->  Bitmap Index Scan on brin_hot_2_b_idx
+         Index Cond: (b = 100)
+(4 rows)
+
+SELECT COUNT(*) FROM brin_hot_2 WHERE a = 2 AND b = 100;
+ count 
+-------
+     1
+(1 row)
+
+DROP TABLE brin_hot_2;
+-- Test that updates to indexed columns are still propagated to the
+-- BRIN column.
+-- https://postgr.es/m/05ebcb44-f383-86e3-4f31-0a97a55634cf@enterprisedb.com
+CREATE TABLE brin_hot_3 (a int, filler text) WITH (fillfactor = 10);
+INSERT INTO brin_hot_3 SELECT 1, repeat(' ', 500) FROM generate_series(1, 20);
+CREATE INDEX ON brin_hot_3 USING brin (a) WITH (pages_per_range = 1);
+UPDATE brin_hot_3 SET a = 2;
+EXPLAIN (COSTS OFF) SELECT * FROM brin_hot_3 WHERE a = 2;
+                 QUERY PLAN                  
+---------------------------------------------
+ Bitmap Heap Scan on brin_hot_3
+   Recheck Cond: (a = 2)
+   ->  Bitmap Index Scan on brin_hot_3_a_idx
+         Index Cond: (a = 2)
+(4 rows)
+
+SELECT COUNT(*) FROM brin_hot_3 WHERE a = 2;
+ count 
+-------
+    20
+(1 row)
+
+DROP TABLE brin_hot_3;
+SET enable_seqscan = on;
+-- Test that estimation of relation size works with tuples wider than the
+-- relation fillfactor. We create a table with wide inline attributes and
+-- low fillfactor, insert rows and then see how many rows EXPLAIN shows
+-- before running analyze. We disable autovacuum so that it does not
+-- interfere with the test.
+CREATE TABLE table_fillfactor (
+  n char(1000)
+) with (fillfactor=10, autovacuum_enabled=off);
+INSERT INTO table_fillfactor
+SELECT 'x' FROM generate_series(1,1000);
+SELECT * FROM check_estimated_rows('SELECT * FROM table_fillfactor');
+ estimated | actual 
+-----------+--------
+      1000 |   1000
+(1 row)
+
+DROP TABLE table_fillfactor;
+-- Test some rewrites
+CREATE TABLE test_2pc_timestamp (a int) WITH (autovacuum_enabled = false);
+VACUUM ANALYZE test_2pc_timestamp;
+SELECT last_analyze AS last_vacuum_analyze FROM pg_stat_all_tables WHERE relname = 'test_2pc_timestamp' \gset
+BEGIN;
+ALTER TABLE test_2pc_timestamp ALTER COLUMN a TYPE int;
+PREPARE TRANSACTION 'test';
+ERROR:  prepared transactions are disabled
+HINT:  Set "max_prepared_transactions" to a nonzero value.
+COMMIT PREPARED 'test';
+ERROR:  prepared transaction with identifier "test" does not exist
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT last_analyze = :'last_vacuum_analyze'::timestamptz FROM pg_stat_all_tables WHERE relname = 'test_2pc_timestamp';
+ ?column? 
+----------
+ t
+(1 row)
+
+DROP TABLE test_2pc_timestamp;
+CREATE TABLE test_2pc_rewrite_alone (a int);
+INSERT INTO test_2pc_rewrite_alone VALUES (1);
+BEGIN;
+ALTER TABLE test_2pc_rewrite_alone ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+ERROR:  prepared transactions are disabled
+HINT:  Set "max_prepared_transactions" to a nonzero value.
+COMMIT PREPARED 'test';
+ERROR:  prepared transaction with identifier "test" does not exist
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_rewrite_alone';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_2pc_rewrite_alone;
+CREATE TABLE test_2pc (a int);
+INSERT INTO test_2pc VALUES (1);
+BEGIN;
+INSERT INTO test_2pc VALUES (1);
+INSERT INTO test_2pc VALUES (2);
+INSERT INTO test_2pc VALUES (3);
+ALTER TABLE test_2pc ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+ERROR:  prepared transactions are disabled
+HINT:  Set "max_prepared_transactions" to a nonzero value.
+COMMIT PREPARED 'test';
+ERROR:  prepared transaction with identifier "test" does not exist
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         4 |          1 |          3
+(1 row)
+
+DROP TABLE test_2pc;
+CREATE TABLE test_2pc_multi (a int);
+INSERT INTO test_2pc_multi VALUES (1);
+BEGIN;
+INSERT INTO test_2pc_multi VALUES (1);
+INSERT INTO test_2pc_multi VALUES (2);
+ALTER TABLE test_2pc_multi ALTER COLUMN a TYPE bigint;
+INSERT INTO test_2pc_multi VALUES (3);
+INSERT INTO test_2pc_multi VALUES (4);
+ALTER TABLE test_2pc_multi ALTER COLUMN a TYPE int;
+INSERT INTO test_2pc_multi VALUES (5);
+PREPARE TRANSACTION 'test';
+ERROR:  prepared transactions are disabled
+HINT:  Set "max_prepared_transactions" to a nonzero value.
+COMMIT PREPARED 'test';
+ERROR:  prepared transaction with identifier "test" does not exist
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_multi';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         6 |          1 |          5
+(1 row)
+
+DROP TABLE test_2pc_multi;
+CREATE TABLE test_2pc_rewrite_alone_abort (a int);
+INSERT INTO test_2pc_rewrite_alone_abort VALUES (1);
+BEGIN;
+ALTER TABLE test_2pc_rewrite_alone_abort ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+ERROR:  prepared transactions are disabled
+HINT:  Set "max_prepared_transactions" to a nonzero value.
+ROLLBACK PREPARED 'test';
+ERROR:  prepared transaction with identifier "test" does not exist
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_rewrite_alone_abort';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_2pc_rewrite_alone_abort;
+CREATE TABLE test_2pc_abort (a int);
+INSERT INTO test_2pc_abort VALUES (1);
+BEGIN;
+INSERT INTO test_2pc_abort VALUES (1);
+INSERT INTO test_2pc_abort VALUES (2);
+ALTER TABLE test_2pc_abort ALTER COLUMN a TYPE bigint;
+INSERT INTO test_2pc_abort VALUES (3);
+PREPARE TRANSACTION 'test';
+ERROR:  prepared transactions are disabled
+HINT:  Set "max_prepared_transactions" to a nonzero value.
+ROLLBACK PREPARED 'test';
+ERROR:  prepared transaction with identifier "test" does not exist
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_abort';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         4 |          1 |          3
+(1 row)
+
+DROP TABLE test_2pc_abort;
+CREATE TABLE test_2pc_savepoint (a int);
+INSERT INTO test_2pc_savepoint VALUES (1);
+BEGIN;
+SAVEPOINT a;
+INSERT INTO test_2pc_savepoint VALUES (1);
+INSERT INTO test_2pc_savepoint VALUES (2);
+ALTER TABLE test_2pc_savepoint ALTER COLUMN a TYPE bigint;
+SAVEPOINT b;
+INSERT INTO test_2pc_savepoint VALUES (3);
+ALTER TABLE test_2pc_savepoint ALTER COLUMN a TYPE int;
+SAVEPOINT c;
+INSERT INTO test_2pc_savepoint VALUES (4);
+INSERT INTO test_2pc_savepoint VALUES (5);
+ROLLBACK TO SAVEPOINT b;
+PREPARE TRANSACTION 'test';
+ERROR:  prepared transactions are disabled
+HINT:  Set "max_prepared_transactions" to a nonzero value.
+COMMIT PREPARED 'test';
+ERROR:  prepared transaction with identifier "test" does not exist
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_savepoint';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         6 |          1 |          5
+(1 row)
+
+DROP TABLE test_2pc_savepoint;
+-- Rewrite without 2PC
+CREATE TABLE test_timestamp (a int) WITH (autovacuum_enabled = false);
+VACUUM ANALYZE test_timestamp;
+SELECT last_analyze AS last_vacuum_analyze FROM pg_stat_all_tables WHERE relname = 'test_timestamp' \gset
+ALTER TABLE test_timestamp ALTER COLUMN a TYPE bigint;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT last_analyze = :'last_vacuum_analyze'::timestamptz FROM pg_stat_all_tables WHERE relname = 'test_timestamp';
+ ?column? 
+----------
+ t
+(1 row)
+
+DROP TABLE test_timestamp;
+CREATE TABLE test_alone (a int);
+INSERT INTO test_alone VALUES (1);
+BEGIN;
+ALTER TABLE test_alone ALTER COLUMN a TYPE bigint;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_alone';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_alone;
+CREATE TABLE test (a int);
+INSERT INTO test VALUES (1);
+BEGIN;
+INSERT INTO test VALUES (1);
+INSERT INTO test VALUES (2);
+INSERT INTO test VALUES (3);
+ALTER TABLE test ALTER COLUMN a TYPE bigint;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         4 |          4 |          0
+(1 row)
+
+DROP TABLE test;
+CREATE TABLE test_multi (a int);
+INSERT INTO test_multi VALUES (1);
+BEGIN;
+INSERT INTO test_multi VALUES (1);
+INSERT INTO test_multi VALUES (2);
+ALTER TABLE test_multi ALTER COLUMN a TYPE bigint;
+INSERT INTO test_multi VALUES (3);
+INSERT INTO test_multi VALUES (4);
+ALTER TABLE test_multi ALTER COLUMN a TYPE int;
+INSERT INTO test_multi VALUES (5);
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_multi';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         6 |          6 |          0
+(1 row)
+
+DROP TABLE test_multi;
+CREATE TABLE test_rewrite_alone_abort (a int);
+INSERT INTO test_rewrite_alone_abort VALUES (1);
+BEGIN;
+ALTER TABLE test_rewrite_alone_abort ALTER COLUMN a TYPE bigint;
+ROLLBACK;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_rewrite_alone_abort';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_rewrite_alone_abort;
+CREATE TABLE test_abort (a int);
+INSERT INTO test_abort VALUES (1);
+BEGIN;
+INSERT INTO test_abort VALUES (1);
+INSERT INTO test_abort VALUES (2);
+ALTER TABLE test_abort ALTER COLUMN a TYPE bigint;
+INSERT INTO test_abort VALUES (3);
+ROLLBACK;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_abort';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         4 |          1 |          3
+(1 row)
+
+DROP TABLE test_abort;
+CREATE TABLE test_savepoint (a int);
+INSERT INTO test_savepoint VALUES (1);
+BEGIN;
+SAVEPOINT a;
+INSERT INTO test_savepoint VALUES (1);
+INSERT INTO test_savepoint VALUES (2);
+ALTER TABLE test_savepoint ALTER COLUMN a TYPE bigint;
+SAVEPOINT b;
+INSERT INTO test_savepoint VALUES (3);
+ALTER TABLE test_savepoint ALTER COLUMN a TYPE int;
+SAVEPOINT c;
+INSERT INTO test_savepoint VALUES (4);
+INSERT INTO test_savepoint VALUES (5);
+ROLLBACK TO SAVEPOINT b;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_savepoint';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         6 |          3 |          3
+(1 row)
+
+DROP TABLE test_savepoint;
+CREATE TABLE test_tbs (a int);
+INSERT INTO test_tbs VALUES (1);
+ALTER TABLE test_tbs SET TABLESPACE pg_default;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_tbs';
+ n_tup_ins | n_live_tup | n_dead_tup 
+-----------+------------+------------
+         1 |          1 |          0
+(1 row)
+
+DROP TABLE test_tbs;
+-- End of Stats Test
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 8768e0f27fd..4130f9254a5 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -944,4 +944,190 @@ SELECT * FROM check_estimated_rows('SELECT * FROM table_fillfactor');
 
 DROP TABLE table_fillfactor;
 
+-- Test some rewrites
+CREATE TABLE test_2pc_timestamp (a int) WITH (autovacuum_enabled = false);
+VACUUM ANALYZE test_2pc_timestamp;
+SELECT last_analyze AS last_vacuum_analyze FROM pg_stat_all_tables WHERE relname = 'test_2pc_timestamp' \gset
+BEGIN;
+ALTER TABLE test_2pc_timestamp ALTER COLUMN a TYPE int;
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+SELECT last_analyze = :'last_vacuum_analyze'::timestamptz FROM pg_stat_all_tables WHERE relname = 'test_2pc_timestamp';
+DROP TABLE test_2pc_timestamp;
+
+CREATE TABLE test_2pc_rewrite_alone (a int);
+INSERT INTO test_2pc_rewrite_alone VALUES (1);
+BEGIN;
+ALTER TABLE test_2pc_rewrite_alone ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_rewrite_alone';
+DROP TABLE test_2pc_rewrite_alone;
+
+CREATE TABLE test_2pc (a int);
+INSERT INTO test_2pc VALUES (1);
+BEGIN;
+INSERT INTO test_2pc VALUES (1);
+INSERT INTO test_2pc VALUES (2);
+INSERT INTO test_2pc VALUES (3);
+ALTER TABLE test_2pc ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc';
+DROP TABLE test_2pc;
+
+CREATE TABLE test_2pc_multi (a int);
+INSERT INTO test_2pc_multi VALUES (1);
+BEGIN;
+INSERT INTO test_2pc_multi VALUES (1);
+INSERT INTO test_2pc_multi VALUES (2);
+ALTER TABLE test_2pc_multi ALTER COLUMN a TYPE bigint;
+INSERT INTO test_2pc_multi VALUES (3);
+INSERT INTO test_2pc_multi VALUES (4);
+ALTER TABLE test_2pc_multi ALTER COLUMN a TYPE int;
+INSERT INTO test_2pc_multi VALUES (5);
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_multi';
+DROP TABLE test_2pc_multi;
+
+CREATE TABLE test_2pc_rewrite_alone_abort (a int);
+INSERT INTO test_2pc_rewrite_alone_abort VALUES (1);
+BEGIN;
+ALTER TABLE test_2pc_rewrite_alone_abort ALTER COLUMN a TYPE bigint;
+PREPARE TRANSACTION 'test';
+ROLLBACK PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_rewrite_alone_abort';
+DROP TABLE test_2pc_rewrite_alone_abort;
+
+CREATE TABLE test_2pc_abort (a int);
+INSERT INTO test_2pc_abort VALUES (1);
+BEGIN;
+INSERT INTO test_2pc_abort VALUES (1);
+INSERT INTO test_2pc_abort VALUES (2);
+ALTER TABLE test_2pc_abort ALTER COLUMN a TYPE bigint;
+INSERT INTO test_2pc_abort VALUES (3);
+PREPARE TRANSACTION 'test';
+ROLLBACK PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_abort';
+DROP TABLE test_2pc_abort;
+
+CREATE TABLE test_2pc_savepoint (a int);
+INSERT INTO test_2pc_savepoint VALUES (1);
+BEGIN;
+SAVEPOINT a;
+INSERT INTO test_2pc_savepoint VALUES (1);
+INSERT INTO test_2pc_savepoint VALUES (2);
+ALTER TABLE test_2pc_savepoint ALTER COLUMN a TYPE bigint;
+SAVEPOINT b;
+INSERT INTO test_2pc_savepoint VALUES (3);
+ALTER TABLE test_2pc_savepoint ALTER COLUMN a TYPE int;
+SAVEPOINT c;
+INSERT INTO test_2pc_savepoint VALUES (4);
+INSERT INTO test_2pc_savepoint VALUES (5);
+ROLLBACK TO SAVEPOINT b;
+PREPARE TRANSACTION 'test';
+COMMIT PREPARED 'test';
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_2pc_savepoint';
+DROP TABLE test_2pc_savepoint;
+
+-- Rewrite without 2PC
+CREATE TABLE test_timestamp (a int) WITH (autovacuum_enabled = false);
+VACUUM ANALYZE test_timestamp;
+SELECT last_analyze AS last_vacuum_analyze FROM pg_stat_all_tables WHERE relname = 'test_timestamp' \gset
+ALTER TABLE test_timestamp ALTER COLUMN a TYPE bigint;
+SELECT pg_stat_force_next_flush();
+SELECT last_analyze = :'last_vacuum_analyze'::timestamptz FROM pg_stat_all_tables WHERE relname = 'test_timestamp';
+DROP TABLE test_timestamp;
+
+CREATE TABLE test_alone (a int);
+INSERT INTO test_alone VALUES (1);
+BEGIN;
+ALTER TABLE test_alone ALTER COLUMN a TYPE bigint;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_alone';
+DROP TABLE test_alone;
+
+CREATE TABLE test (a int);
+INSERT INTO test VALUES (1);
+BEGIN;
+INSERT INTO test VALUES (1);
+INSERT INTO test VALUES (2);
+INSERT INTO test VALUES (3);
+ALTER TABLE test ALTER COLUMN a TYPE bigint;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test';
+DROP TABLE test;
+
+CREATE TABLE test_multi (a int);
+INSERT INTO test_multi VALUES (1);
+BEGIN;
+INSERT INTO test_multi VALUES (1);
+INSERT INTO test_multi VALUES (2);
+ALTER TABLE test_multi ALTER COLUMN a TYPE bigint;
+INSERT INTO test_multi VALUES (3);
+INSERT INTO test_multi VALUES (4);
+ALTER TABLE test_multi ALTER COLUMN a TYPE int;
+INSERT INTO test_multi VALUES (5);
+COMMIT;
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_multi';
+DROP TABLE test_multi;
+
+CREATE TABLE test_rewrite_alone_abort (a int);
+INSERT INTO test_rewrite_alone_abort VALUES (1);
+BEGIN;
+ALTER TABLE test_rewrite_alone_abort ALTER COLUMN a TYPE bigint;
+ROLLBACK;
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_rewrite_alone_abort';
+DROP TABLE test_rewrite_alone_abort;
+
+CREATE TABLE test_abort (a int);
+INSERT INTO test_abort VALUES (1);
+BEGIN;
+INSERT INTO test_abort VALUES (1);
+INSERT INTO test_abort VALUES (2);
+ALTER TABLE test_abort ALTER COLUMN a TYPE bigint;
+INSERT INTO test_abort VALUES (3);
+ROLLBACK;
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_abort';
+DROP TABLE test_abort;
+
+CREATE TABLE test_savepoint (a int);
+INSERT INTO test_savepoint VALUES (1);
+BEGIN;
+SAVEPOINT a;
+INSERT INTO test_savepoint VALUES (1);
+INSERT INTO test_savepoint VALUES (2);
+ALTER TABLE test_savepoint ALTER COLUMN a TYPE bigint;
+SAVEPOINT b;
+INSERT INTO test_savepoint VALUES (3);
+ALTER TABLE test_savepoint ALTER COLUMN a TYPE int;
+SAVEPOINT c;
+INSERT INTO test_savepoint VALUES (4);
+INSERT INTO test_savepoint VALUES (5);
+ROLLBACK TO SAVEPOINT b;
+COMMIT;
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_savepoint';
+DROP TABLE test_savepoint;
+
+CREATE TABLE test_tbs (a int);
+INSERT INTO test_tbs VALUES (1);
+ALTER TABLE test_tbs SET TABLESPACE pg_default;
+SELECT pg_stat_force_next_flush();
+SELECT n_tup_ins, n_live_tup, n_dead_tup FROM pg_stat_all_tables WHERE relname = 'test_tbs';
+DROP TABLE test_tbs;
+
 -- End of Stats Test
-- 
2.34.1

  [text/x-diff] v7-0002-Key-PGSTAT_KIND_RELATION-by-relfile-locator.patch (26.3K, ../aQ3X20hbqoThQXgp@ip-10-97-1-34.eu-west-3.compute.internal/3-v7-0002-Key-PGSTAT_KIND_RELATION-by-relfile-locator.patch)
  download | inline diff:
From 2cc88c7d89f95a7f72476593e861721236d12354 Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Date: Wed, 1 Oct 2025 09:45:26 +0000
Subject: [PATCH v7 2/3] Key PGSTAT_KIND_RELATION by relfile locator

This patch changes the key used for the PGSTAT_KIND_RELATION statistic kind.
Instead of the relation oid, it now relies on:

- dboid (linked to RelFileLocator's dbOid)
- objoid which is the result of a new macro (namely RelFileLocatorToPgStatObjid())
that computes an objoid based on the RelFileLocator's spcOid and the
RelFileLocator's relNumber.

That will allow us to add new stats (add writes counters) and ensure that some
counters (n_dead_tup and friends) are replicated.

The patch introduces pgstat_reloid_to_relfilelocator() to 1) avoid calling
RelationIdGetRelation() to get the relfilelocator based on the relation oid
and 2) handle the partitioned table case.

Please note that:

- when running pg_stat_have_stats('relation',...) we now need to be connected
to the database that hosts the relation. As pg_stat_have_stats() is not
documented publicly, then the changes done in 029_stats_restart.pl look
enough.

- this patch does not handle rewrites so some tests are failing. It's only
intent is to ease the review and should not be pushed without being
merged with the following patch that handles the rewrites.

- it can be used to test that stats are incremented correctly and that we're
able to retrieve them as long as rewrites are not involved.
---
 src/backend/access/heap/vacuumlazy.c         |   3 +-
 src/backend/postmaster/autovacuum.c          |   9 +-
 src/backend/utils/activity/pgstat_relation.c | 234 +++++++++++++++----
 src/backend/utils/adt/pgstatfuncs.c          |  22 +-
 src/include/pgstat.h                         |  18 +-
 src/include/utils/pgstat_internal.h          |   1 +
 src/test/recovery/t/029_stats_restart.pl     |  40 ++--
 7 files changed, 249 insertions(+), 78 deletions(-)
   3.3% src/backend/postmaster/
  64.6% src/backend/utils/activity/
   5.3% src/backend/utils/adt/
   7.0% src/include/
  18.7% src/test/recovery/t/

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 61fe623cc60..073f1ff3fe4 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -947,8 +947,7 @@ heap_vacuum_rel(Relation rel, const VacuumParams params,
 	 * soon in cases where the failsafe prevented significant amounts of heap
 	 * vacuuming.
 	 */
-	pgstat_report_vacuum(RelationGetRelid(rel),
-						 rel->rd_rel->relisshared,
+	pgstat_report_vacuum(rel->rd_locator,
 						 Max(vacrel->new_live_tuples, 0),
 						 vacrel->recently_dead_tuples +
 						 vacrel->missed_dead_tuples,
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index ed19c74bb19..662495c72fc 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -2048,8 +2048,7 @@ do_autovacuum(void)
 
 		/* Fetch reloptions and the pgstat entry for this table */
 		relopts = extract_autovac_opts(tuple, pg_class_desc);
-		tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
-												  relid);
+		tabentry = pgstat_fetch_stat_tabentry_ext(relid);
 
 		/* Check if it needs vacuum or analyze */
 		relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
@@ -2141,8 +2140,7 @@ do_autovacuum(void)
 		}
 
 		/* Fetch the pgstat entry for this table */
-		tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
-												  relid);
+		tabentry = pgstat_fetch_stat_tabentry_ext(relid);
 
 		relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
 								  effective_multixact_freeze_max_age,
@@ -2939,8 +2937,7 @@ recheck_relation_needs_vacanalyze(Oid relid,
 	PgStat_StatTabEntry *tabentry;
 
 	/* fetch the pgstat table entry */
-	tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
-											  relid);
+	tabentry = pgstat_fetch_stat_tabentry_ext(relid);
 
 	relation_needs_vacanalyze(relid, avopts, classForm, tabentry,
 							  effective_multixact_freeze_max_age,
diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c
index 1de477cbeeb..7debb14bb5d 100644
--- a/src/backend/utils/activity/pgstat_relation.c
+++ b/src/backend/utils/activity/pgstat_relation.c
@@ -17,12 +17,17 @@
 
 #include "postgres.h"
 
+#include "access/htup_details.h"
 #include "access/twophase_rmgr.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
+#include "catalog/pg_tablespace.h"
+#include "storage/lmgr.h"
 #include "utils/memutils.h"
 #include "utils/pgstat_internal.h"
 #include "utils/rel.h"
+#include "utils/relmapper.h"
+#include "utils/syscache.h"
 #include "utils/timestamp.h"
 
 
@@ -36,13 +41,12 @@ typedef struct TwoPhasePgStatRecord
 	PgStat_Counter inserted_pre_truncdrop;
 	PgStat_Counter updated_pre_truncdrop;
 	PgStat_Counter deleted_pre_truncdrop;
-	Oid			id;				/* table's OID */
-	bool		shared;			/* is it a shared catalog? */
+	RelFileLocator locator;		/* table's rd_locator */
 	bool		truncdropped;	/* was the relation truncated/dropped? */
 } TwoPhasePgStatRecord;
 
 
-static PgStat_TableStatus *pgstat_prep_relation_pending(Oid rel_id, bool isshared);
+static PgStat_TableStatus *pgstat_prep_relation_pending(RelFileLocator locator);
 static void add_tabstat_xact_level(PgStat_TableStatus *pgstat_info, int nest_level);
 static void ensure_tabstat_xact_level(PgStat_TableStatus *pgstat_info);
 static void save_truncdrop_counters(PgStat_TableXactStatus *trans, bool is_drop);
@@ -60,8 +64,7 @@ pgstat_copy_relation_stats(Relation dst, Relation src)
 	PgStatShared_Relation *dstshstats;
 	PgStat_EntryRef *dst_ref;
 
-	srcstats = pgstat_fetch_stat_tabentry_ext(src->rd_rel->relisshared,
-											  RelationGetRelid(src));
+	srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src));
 	if (!srcstats)
 		return;
 
@@ -94,8 +97,10 @@ pgstat_init_relation(Relation rel)
 
 	/*
 	 * We only count stats for relations with storage and partitioned tables
+	 * and we don't count stats generated during a rewrite.
 	 */
-	if (!RELKIND_HAS_STORAGE(relkind) && relkind != RELKIND_PARTITIONED_TABLE)
+	if ((!RELKIND_HAS_STORAGE(relkind) && relkind != RELKIND_PARTITIONED_TABLE) ||
+		OidIsValid(rel->rd_rel->relrewrite))
 	{
 		rel->pgstat_enabled = false;
 		rel->pgstat_info = NULL;
@@ -130,12 +135,38 @@ pgstat_init_relation(Relation rel)
 void
 pgstat_assoc_relation(Relation rel)
 {
+	RelFileLocator locator;
+
 	Assert(rel->pgstat_enabled);
 	Assert(rel->pgstat_info == NULL);
 
+	/*
+	 * Don't associate stats for relations without storage and non partitioned
+	 * tables.
+	 */
+	if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind) &&
+		rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+		return;
+
+	if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+		locator = rel->rd_locator;
+	else
+	{
+		/*
+		 * Partitioned tables don't have storage, so construct a synthetic
+		 * locator for statistics tracking. Use the relation OID as relNumber.
+		 * No collision with regular relations is possible because relNumbers
+		 * are also assigned from the pg_class OID space (see
+		 * GetNewRelFileNumber()), making each value unique across the
+		 * database regardless of spcOid.
+		 */
+		locator.dbOid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
+		locator.spcOid = InvalidOid;
+		locator.relNumber = rel->rd_id;
+	}
+
 	/* Else find or make the PgStat_TableStatus entry, and update link */
-	rel->pgstat_info = pgstat_prep_relation_pending(RelationGetRelid(rel),
-													rel->rd_rel->relisshared);
+	rel->pgstat_info = pgstat_prep_relation_pending(locator);
 
 	/* don't allow link a stats to multiple relcache entries */
 	Assert(rel->pgstat_info->relation == NULL);
@@ -167,9 +198,13 @@ pgstat_unlink_relation(Relation rel)
 void
 pgstat_create_relation(Relation rel)
 {
+	/* don't track stats for relations without storage */
+	if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
+		return;
+
 	pgstat_create_transactional(PGSTAT_KIND_RELATION,
-								rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId,
-								RelationGetRelid(rel));
+								rel->rd_locator.dbOid,
+								RelFileLocatorToPgStatObjid(rel->rd_locator));
 }
 
 /*
@@ -181,9 +216,13 @@ pgstat_drop_relation(Relation rel)
 	int			nest_level = GetCurrentTransactionNestLevel();
 	PgStat_TableStatus *pgstat_info;
 
+	/* don't track stats for relations without storage */
+	if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
+		return;
+
 	pgstat_drop_transactional(PGSTAT_KIND_RELATION,
-							  rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId,
-							  RelationGetRelid(rel));
+							  rel->rd_locator.dbOid,
+							  RelFileLocatorToPgStatObjid(rel->rd_locator));
 
 	if (!pgstat_should_count_relation(rel))
 		return;
@@ -207,14 +246,12 @@ pgstat_drop_relation(Relation rel)
  * Report that the table was just vacuumed and flush IO statistics.
  */
 void
-pgstat_report_vacuum(Oid tableoid, bool shared,
-					 PgStat_Counter livetuples, PgStat_Counter deadtuples,
-					 TimestampTz starttime)
+pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetuples,
+					 PgStat_Counter deadtuples, TimestampTz starttime)
 {
 	PgStat_EntryRef *entry_ref;
 	PgStatShared_Relation *shtabentry;
 	PgStat_StatTabEntry *tabentry;
-	Oid			dboid = (shared ? InvalidOid : MyDatabaseId);
 	TimestampTz ts;
 	PgStat_Counter elapsedtime;
 
@@ -227,7 +264,7 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
 
 	/* block acquiring lock for the same reason as pgstat_report_autovac() */
 	entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION,
-											dboid, tableoid, false);
+											locator.dbOid, RelFileLocatorToPgStatObjid(locator), false);
 
 	shtabentry = (PgStatShared_Relation *) entry_ref->shared_stats;
 	tabentry = &shtabentry->stats;
@@ -286,9 +323,9 @@ pgstat_report_analyze(Relation rel,
 	PgStat_EntryRef *entry_ref;
 	PgStatShared_Relation *shtabentry;
 	PgStat_StatTabEntry *tabentry;
-	Oid			dboid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
 	TimestampTz ts;
 	PgStat_Counter elapsedtime;
+	RelFileLocator locator;
 
 	if (!pgstat_track_counts)
 		return;
@@ -326,9 +363,26 @@ pgstat_report_analyze(Relation rel,
 	ts = GetCurrentTimestamp();
 	elapsedtime = TimestampDifferenceMilliseconds(starttime, ts);
 
+	if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+		locator = rel->rd_locator;
+	else
+	{
+		/*
+		 * Partitioned tables don't have storage, so construct a synthetic
+		 * locator for statistics tracking. Use the relation OID as relNumber.
+		 * No collision with regular relations is possible because relNumbers
+		 * are also assigned from the pg_class OID space (see
+		 * GetNewRelFileNumber()), making each value unique across the
+		 * database regardless of spcOid.
+		 */
+		locator.dbOid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
+		locator.spcOid = InvalidOid;
+		locator.relNumber = rel->rd_id;
+	}
 	/* block acquiring lock for the same reason as pgstat_report_autovac() */
-	entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, dboid,
-											RelationGetRelid(rel),
+	entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION,
+											locator.dbOid,
+											RelFileLocatorToPgStatObjid(locator),
 											false);
 	/* can't get dropped while accessed */
 	Assert(entry_ref != NULL && entry_ref->shared_stats != NULL);
@@ -469,7 +523,7 @@ pgstat_update_heap_dead_tuples(Relation rel, int delta)
 PgStat_StatTabEntry *
 pgstat_fetch_stat_tabentry(Oid relid)
 {
-	return pgstat_fetch_stat_tabentry_ext(IsSharedRelation(relid), relid);
+	return pgstat_fetch_stat_tabentry_ext(relid);
 }
 
 /*
@@ -477,12 +531,19 @@ pgstat_fetch_stat_tabentry(Oid relid)
  * whether the to-be-accessed table is a shared relation or not.
  */
 PgStat_StatTabEntry *
-pgstat_fetch_stat_tabentry_ext(bool shared, Oid reloid)
+pgstat_fetch_stat_tabentry_ext(Oid reloid)
 {
-	Oid			dboid = (shared ? InvalidOid : MyDatabaseId);
+	PgStat_StatTabEntry *tabentry;
+	RelFileLocator locator;
+
+	if (!pgstat_reloid_to_relfilelocator(reloid, &locator))
+		return NULL;
 
-	return (PgStat_StatTabEntry *)
-		pgstat_fetch_entry(PGSTAT_KIND_RELATION, dboid, reloid);
+	/* fetch the stats entry using the relfilenode based key */
+	tabentry = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION,
+														  locator.dbOid,
+														  RelFileLocatorToPgStatObjid(locator));
+	return tabentry;
 }
 
 /*
@@ -504,14 +565,17 @@ find_tabstat_entry(Oid rel_id)
 	PgStat_TableXactStatus *trans;
 	PgStat_TableStatus *tabentry = NULL;
 	PgStat_TableStatus *tablestatus = NULL;
+	RelFileLocator locator;
+
+	if (!pgstat_reloid_to_relfilelocator(rel_id, &locator))
+		return NULL;
+
+	entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION,
+										   locator.dbOid,
+										   RelFileLocatorToPgStatObjid(locator));
 
-	entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, MyDatabaseId, rel_id);
 	if (!entry_ref)
-	{
-		entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, InvalidOid, rel_id);
-		if (!entry_ref)
-			return tablestatus;
-	}
+		return tablestatus;
 
 	tabentry = (PgStat_TableStatus *) entry_ref->pending;
 	tablestatus = palloc(sizeof(PgStat_TableStatus));
@@ -707,8 +771,12 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state)
 		record.inserted_pre_truncdrop = trans->inserted_pre_truncdrop;
 		record.updated_pre_truncdrop = trans->updated_pre_truncdrop;
 		record.deleted_pre_truncdrop = trans->deleted_pre_truncdrop;
-		record.id = tabstat->id;
-		record.shared = tabstat->shared;
+
+		if (tabstat->relation != NULL)
+			record.locator = tabstat->relation->rd_locator;
+		else
+			record.locator = tabstat->locator;
+
 		record.truncdropped = trans->truncdropped;
 
 		RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0,
@@ -751,7 +819,7 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info,
 	PgStat_TableStatus *pgstat_info;
 
 	/* Find or create a tabstat entry for the rel */
-	pgstat_info = pgstat_prep_relation_pending(rec->id, rec->shared);
+	pgstat_info = pgstat_prep_relation_pending(rec->locator);
 
 	/* Same math as in AtEOXact_PgStat, commit case */
 	pgstat_info->counts.tuples_inserted += rec->tuples_inserted;
@@ -786,8 +854,8 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
 	TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata;
 	PgStat_TableStatus *pgstat_info;
 
-	/* Find or create a tabstat entry for the rel */
-	pgstat_info = pgstat_prep_relation_pending(rec->id, rec->shared);
+	/* Find or create a tabstat entry for the target locator */
+	pgstat_info = pgstat_prep_relation_pending(rec->locator);
 
 	/* Same math as in AtEOXact_PgStat, abort case */
 	if (rec->truncdropped)
@@ -921,17 +989,21 @@ pgstat_relation_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
  * initialized if not exists.
  */
 static PgStat_TableStatus *
-pgstat_prep_relation_pending(Oid rel_id, bool isshared)
+pgstat_prep_relation_pending(RelFileLocator locator)
 {
 	PgStat_EntryRef *entry_ref;
 	PgStat_TableStatus *pending;
+	uint64		objid;
+
+	objid = RelFileLocatorToPgStatObjid(locator);
 
 	entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_RELATION,
-										  isshared ? InvalidOid : MyDatabaseId,
-										  rel_id, NULL);
+										  locator.dbOid,
+										  objid, NULL);
+
 	pending = entry_ref->pending;
-	pending->id = rel_id;
-	pending->shared = isshared;
+	pending->id = objid;
+	pending->locator = locator;
 
 	return pending;
 }
@@ -1010,3 +1082,83 @@ restore_truncdrop_counters(PgStat_TableXactStatus *trans)
 		trans->tuples_deleted = trans->deleted_pre_truncdrop;
 	}
 }
+
+/*
+ * Convert a relation OID to its corresponding RelFileLocator for statistics
+ * tracking purposes.
+ *
+ * Returns true on success, false if the relation doesn't need statistics
+ * tracking.
+ *
+ * For partitioned tables, constructs a synthetic locator using the relation
+ * OID as relNumber, since they don't have storage.
+ */
+bool
+pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator)
+{
+	HeapTuple	tuple;
+	Form_pg_class relform;
+	bool		result = true;
+
+	/* get the relation's tuple from pg_class */
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(reloid));
+
+	if (!HeapTupleIsValid(tuple))
+		return false;
+
+	relform = (Form_pg_class) GETSTRUCT(tuple);
+
+	/* skip relations without storage and non partitioned tables */
+	if (!RELKIND_HAS_STORAGE(relform->relkind) &&
+		relform->relkind != RELKIND_PARTITIONED_TABLE)
+	{
+		ReleaseSysCache(tuple);
+		return false;
+	}
+
+	if (relform->relkind != RELKIND_PARTITIONED_TABLE)
+	{
+		/* build the RelFileLocator */
+		locator->relNumber = relform->relfilenode;
+		locator->spcOid = relform->reltablespace;
+
+		/* handle default tablespace */
+		if (!OidIsValid(locator->spcOid))
+			locator->spcOid = MyDatabaseTableSpace;
+
+		/* handle dbOid for global vs local relations */
+		if (locator->spcOid == GLOBALTABLESPACE_OID)
+			locator->dbOid = InvalidOid;
+		else
+			locator->dbOid = MyDatabaseId;
+
+		/* handle mapped relations */
+		if (!RelFileNumberIsValid(locator->relNumber))
+		{
+			locator->relNumber = RelationMapOidToFilenumber(reloid,
+															relform->relisshared);
+			if (!RelFileNumberIsValid(locator->relNumber))
+			{
+				ReleaseSysCache(tuple);
+				return false;
+			}
+		}
+	}
+	else
+	{
+		/*
+		 * Partitioned tables don't have storage, so construct a synthetic
+		 * locator for statistics tracking. Use the relation OID as relNumber.
+		 * No collision with regular relations is possible because relNumbers
+		 * are also assigned from the pg_class OID space (see
+		 * GetNewRelFileNumber()), making each value unique across the
+		 * database regardless of spcOid.
+		 */
+		locator->dbOid = (relform->relisshared ? InvalidOid : MyDatabaseId);
+		locator->spcOid = InvalidOid;
+		locator->relNumber = relform->oid;
+	}
+
+	ReleaseSysCache(tuple);
+	return result;
+}
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a710508979e..7924cdf5b97 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -23,13 +23,13 @@
 #include "common/ip.h"
 #include "funcapi.h"
 #include "miscadmin.h"
-#include "pgstat.h"
 #include "postmaster/bgworker.h"
 #include "replication/logicallauncher.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
+#include "utils/pgstat_internal.h"
 #include "utils/timestamp.h"
 
 #define UINT32_ACCESS_ONCE(var)		 ((uint32)(*((volatile uint32 *)&(var))))
@@ -1949,9 +1949,14 @@ Datum
 pg_stat_reset_single_table_counters(PG_FUNCTION_ARGS)
 {
 	Oid			taboid = PG_GETARG_OID(0);
-	Oid			dboid = (IsSharedRelation(taboid) ? InvalidOid : MyDatabaseId);
+	RelFileLocator locator;
 
-	pgstat_reset(PGSTAT_KIND_RELATION, dboid, taboid);
+	/* Get the stats locator from the relation OID */
+	if (!pgstat_reloid_to_relfilelocator(taboid, &locator))
+		PG_RETURN_VOID();
+
+	pgstat_reset(PGSTAT_KIND_RELATION, locator.dbOid,
+				 RelFileLocatorToPgStatObjid(locator));
 
 	PG_RETURN_VOID();
 }
@@ -2290,5 +2295,16 @@ pg_stat_have_stats(PG_FUNCTION_ARGS)
 	uint64		objid = PG_GETARG_INT64(2);
 	PgStat_Kind kind = pgstat_get_kind_from_str(stats_type);
 
+	/* Convert relation OID to relfilenode objid */
+	if (kind == PGSTAT_KIND_RELATION)
+	{
+		RelFileLocator locator;
+
+		if (!pgstat_reloid_to_relfilelocator(objid, &locator))
+			PG_RETURN_BOOL(false);
+
+		objid = RelFileLocatorToPgStatObjid(locator);
+	}
+
 	PG_RETURN_BOOL(pgstat_have_entry(kind, dboid, objid));
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 7ae503e71a2..5d0fe79f7e3 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -16,6 +16,7 @@
 #include "portability/instr_time.h"
 #include "postmaster/pgarch.h"	/* for MAX_XFN_CHARS */
 #include "replication/conflict.h"
+#include "storage/relfilelocator.h"
 #include "utils/backend_progress.h" /* for backward compatibility */	/* IWYU pragma: export */
 #include "utils/backend_status.h"	/* for backward compatibility */	/* IWYU pragma: export */
 #include "utils/pgstat_kind.h"
@@ -34,6 +35,12 @@
 /* Default directory to store temporary statistics data in */
 #define PG_STAT_TMP_DIR		"pg_stat_tmp"
 
+/*
+ * Build a pgstat key Objid based on a RelFileLocator.
+ */
+#define RelFileLocatorToPgStatObjid(locator) \
+	(((uint64) (locator).spcOid << 32) | (locator).relNumber)
+
 /* Values for track_functions GUC variable --- order is significant! */
 typedef enum TrackFunctionsLevel
 {
@@ -173,11 +180,11 @@ typedef struct PgStat_TableCounts
  */
 typedef struct PgStat_TableStatus
 {
-	Oid			id;				/* table's OID */
-	bool		shared;			/* is it a shared catalog? */
+	uint64		id;				/* hash of relfilelocator for stats key */
 	struct PgStat_TableXactStatus *trans;	/* lowest subxact's counts */
 	PgStat_TableCounts counts;	/* event counts to be sent */
 	Relation	relation;		/* rel that is using this entry */
+	RelFileLocator locator;		/* table's relfilelocator */
 } PgStat_TableStatus;
 
 /* ----------
@@ -664,8 +671,8 @@ extern void pgstat_init_relation(Relation rel);
 extern void pgstat_assoc_relation(Relation rel);
 extern void pgstat_unlink_relation(Relation rel);
 
-extern void pgstat_report_vacuum(Oid tableoid, bool shared,
-								 PgStat_Counter livetuples, PgStat_Counter deadtuples,
+extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetuples,
+								 PgStat_Counter deadtuples,
 								 TimestampTz starttime);
 extern void pgstat_report_analyze(Relation rel,
 								  PgStat_Counter livetuples, PgStat_Counter deadtuples,
@@ -730,8 +737,7 @@ extern void pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
 									  void *recdata, uint32 len);
 
 extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry(Oid relid);
-extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry_ext(bool shared,
-														   Oid reloid);
+extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry_ext(Oid reloid);
 extern PgStat_TableStatus *find_tabstat_entry(Oid rel_id);
 
 
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 4d2b8aa6081..1252249231d 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -718,6 +718,7 @@ extern void PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
 extern bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
 extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
 extern void pgstat_relation_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
+extern bool pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator);
 
 
 /*
diff --git a/src/test/recovery/t/029_stats_restart.pl b/src/test/recovery/t/029_stats_restart.pl
index 021e2bf361f..3a9c05eaf10 100644
--- a/src/test/recovery/t/029_stats_restart.pl
+++ b/src/test/recovery/t/029_stats_restart.pl
@@ -55,10 +55,10 @@ trigger_funcrel_stat();
 
 # verify stats objects exist
 $sect = "initial";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
 	't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
 	't', "$sect: relation stats do exist");
 
 # regular shutdown
@@ -79,10 +79,10 @@ copy($og_stats, $statsfile) or die "Copy failed: $!";
 $node->start;
 
 $sect = "copy";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
 	't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
 	't', "$sect: relation stats do exist");
 
 $node->stop('immediate');
@@ -96,10 +96,10 @@ $node->start;
 
 # stats should have been discarded
 $sect = "post immediate";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
 	'f', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
 	'f', "$sect: relation stats do not exist");
 
 # get rid of backup statsfile
@@ -110,10 +110,10 @@ unlink $statsfile or die "cannot unlink $statsfile $!";
 trigger_funcrel_stat();
 
 $sect = "post immediate, new";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
 	't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
 	't', "$sect: relation stats do exist");
 
 # regular shutdown
@@ -129,10 +129,10 @@ $node->start;
 
 # no stats present due to invalid stats file
 $sect = "invalid_overwrite";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
 	'f', "$sect: function stats do not exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
 	'f', "$sect: relation stats do not exist");
 
 
@@ -145,10 +145,10 @@ append_file($og_stats, "XYZ");
 $node->start;
 
 $sect = "invalid_append";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
 	'f', "$sect: function stats do not exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
 	'f', "$sect: relation stats do not exist");
 
 
@@ -307,9 +307,9 @@ sub trigger_funcrel_stat
 
 sub have_stats
 {
-	my ($kind, $dboid, $objid) = @_;
+	my ($db, $kind, $dboid, $objid) = @_;
 
-	return $node->safe_psql($connect_db,
+	return $node->safe_psql($db,
 		"SELECT pg_stat_have_stats('$kind', $dboid, $objid)");
 }
 
-- 
2.34.1

  [text/x-diff] v7-0003-handle-relation-statistics-correctly-during-rewri.patch (25.9K, ../aQ3X20hbqoThQXgp@ip-10-97-1-34.eu-west-3.compute.internal/4-v7-0003-handle-relation-statistics-correctly-during-rewri.patch)
  download | inline diff:
From 8f748e64a89603f9e7543ff0da30ceccaf7d5edb Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Date: Tue, 4 Nov 2025 13:52:46 +0000
Subject: [PATCH v7 3/3] handle relation statistics correctly during rewrites

Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.

To do so, this patch:

- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.

- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.

- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).

- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.

Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.

The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.

The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
 src/backend/catalog/index.c                  |   2 +-
 src/backend/commands/cluster.c               |   5 +
 src/backend/commands/tablecmds.c             |   6 +
 src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
 src/backend/utils/activity/pgstat_xact.c     |  25 +-
 src/backend/utils/cache/relcache.c           |   6 +
 src/include/pgstat.h                         |   5 +-
 src/tools/pgindent/typedefs.list             |   1 +
 8 files changed, 424 insertions(+), 17 deletions(-)
  92.8% src/backend/utils/activity/
   4.9% src/backend/

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 5d9db167e59..8b6a7652fcf 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName)
 	changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId);
 
 	/* copy over statistics from old to new index */
-	pgstat_copy_relation_stats(newClassRel, oldClassRel);
+	pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false);
 
 	/* Copy data of pg_statistic from the old index to the new one */
 	CopyStatistics(oldIndexId, newIndexId);
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index b55221d44cd..da75dfa6ab8 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class,
 
 		rel1 = relation_open(r1, NoLock);
 		rel2 = relation_open(r2, NoLock);
+
+		/* Mark that a rewrite happened */
+		if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind))
+			pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator);
+
 		rel2->rd_createSubid = rel1->rd_createSubid;
 		rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid;
 		rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 3aac459e483..540923452fb 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode)
 	Oid			reltoastrelid;
 	RelFileNumber newrelfilenumber;
 	RelFileLocator newrlocator;
+	RelFileLocator oldrlocator;
 	List	   *reltoastidxids = NIL;
 	ListCell   *lc;
 
@@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode)
 	newrlocator = rel->rd_locator;
 	newrlocator.relNumber = newrelfilenumber;
 	newrlocator.spcOid = newTableSpace;
+	oldrlocator = rel->rd_locator;
 
 	/* hand off to AM to actually create new rel storage and copy the data */
 	if (rel->rd_rel->relkind == RELKIND_INDEX)
@@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode)
 		table_relation_copy_data(rel, &newrlocator);
 	}
 
+	/* mark that a rewrite happened */
+	if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
+		pgstat_mark_rewrite(oldrlocator, newrlocator);
+
 	/*
 	 * Update the pg_class row.
 	 *
diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c
index 7debb14bb5d..15b4663eb77 100644
--- a/src/backend/utils/activity/pgstat_relation.c
+++ b/src/backend/utils/activity/pgstat_relation.c
@@ -30,6 +30,19 @@
 #include "utils/syscache.h"
 #include "utils/timestamp.h"
 
+/* Pending rewrite operations for stats copying */
+typedef struct PgStat_PendingRewrite
+{
+	RelFileLocator old_locator;
+	RelFileLocator new_locator;
+	RelFileLocator original_locator;
+	int			nest_level;		/* Transaction nesting level where rewrite
+								 * occurred */
+	struct PgStat_PendingRewrite *next;
+} PgStat_PendingRewrite;
+
+/* The pending rewrites list for current transaction */
+static PgStat_PendingRewrite *pending_rewrites = NULL;
 
 /* Record that's written to 2PC state file when pgstat state is persisted */
 typedef struct TwoPhasePgStatRecord
@@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord
 	PgStat_Counter deleted_pre_truncdrop;
 	RelFileLocator locator;		/* table's rd_locator */
 	bool		truncdropped;	/* was the relation truncated/dropped? */
+	RelFileLocator rewrite_old_locator;
+	int			rewrite_nest_level;
 } TwoPhasePgStatRecord;
 
 
@@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans);
 
 
 /*
- * Copy stats between relations. This is used for things like REINDEX
+ * Copy stats between RelFileLocator. This is used for things like REINDEX
  * CONCURRENTLY.
  */
 void
-pgstat_copy_relation_stats(Relation dst, Relation src)
+pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment)
 {
 	PgStat_StatTabEntry *srcstats;
 	PgStatShared_Relation *dstshstats;
 	PgStat_EntryRef *dst_ref;
 
-	srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src));
+	srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION,
+														  src.dbOid,
+														  RelFileLocatorToPgStatObjid(src));
 	if (!srcstats)
 		return;
 
 	dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION,
-										  dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId,
-										  RelationGetRelid(dst),
+										  dst.dbOid,
+										  RelFileLocatorToPgStatObjid(dst),
 										  false);
 
 	dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats;
-	dstshstats->stats = *srcstats;
+
+	if (!increment)
+		dstshstats->stats = *srcstats;
+	else
+	{
+		/* Increment those statistics */
+#define RELFSTAT_ACC(fld, stats_to_add) \
+	(dstshstats->stats.fld += stats_to_add->fld)
+		RELFSTAT_ACC(numscans, srcstats);
+		RELFSTAT_ACC(tuples_returned, srcstats);
+		RELFSTAT_ACC(tuples_fetched, srcstats);
+		RELFSTAT_ACC(tuples_inserted, srcstats);
+		RELFSTAT_ACC(tuples_updated, srcstats);
+		RELFSTAT_ACC(tuples_deleted, srcstats);
+		RELFSTAT_ACC(tuples_hot_updated, srcstats);
+		RELFSTAT_ACC(tuples_newpage_updated, srcstats);
+		RELFSTAT_ACC(live_tuples, srcstats);
+		RELFSTAT_ACC(dead_tuples, srcstats);
+		RELFSTAT_ACC(mod_since_analyze, srcstats);
+		RELFSTAT_ACC(ins_since_vacuum, srcstats);
+		RELFSTAT_ACC(blocks_fetched, srcstats);
+		RELFSTAT_ACC(blocks_hit, srcstats);
+		RELFSTAT_ACC(vacuum_count, srcstats);
+		RELFSTAT_ACC(autovacuum_count, srcstats);
+		RELFSTAT_ACC(analyze_count, srcstats);
+		RELFSTAT_ACC(autoanalyze_count, srcstats);
+		RELFSTAT_ACC(total_vacuum_time, srcstats);
+		RELFSTAT_ACC(total_autovacuum_time, srcstats);
+		RELFSTAT_ACC(total_analyze_time, srcstats);
+		RELFSTAT_ACC(total_autoanalyze_time, srcstats);
+#undef RELFSTAT_ACC
+
+		/* Replace those statistics */
+#define RELFSTAT_REP(fld, stats_to_rep) \
+	(dstshstats->stats.fld = stats_to_rep->fld)
+		RELFSTAT_REP(lastscan, srcstats);
+		RELFSTAT_REP(last_vacuum_time, srcstats);
+		RELFSTAT_REP(last_autovacuum_time, srcstats);
+		RELFSTAT_REP(last_analyze_time, srcstats);
+		RELFSTAT_REP(last_autoanalyze_time, srcstats);
+#undef RELFSTAT_REP
+	}
 
 	pgstat_unlock_entry(dst_ref);
 }
@@ -136,6 +194,7 @@ void
 pgstat_assoc_relation(Relation rel)
 {
 	RelFileLocator locator;
+	PgStat_TableStatus *pgstat_info;
 
 	Assert(rel->pgstat_enabled);
 	Assert(rel->pgstat_info == NULL);
@@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel)
 		locator.relNumber = rel->rd_id;
 	}
 
+	/*
+	 * If this relation was rewritten during the current transaction we may be
+	 * reopening it with its new RelFileLocator. In that case, continue using
+	 * the stats entry associated with the old locator rather than creating a
+	 * new one. This ensures all stats from before and after the rewrite are
+	 * tracked in a single entry which will be properly copied to the new
+	 * locator at transaction commit.
+	 */
+	if (pending_rewrites != NULL)
+	{
+		PgStat_PendingRewrite *rewrite;
+
+		for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next)
+		{
+			if (locator.dbOid == rewrite->new_locator.dbOid &&
+				locator.spcOid == rewrite->new_locator.spcOid &&
+				locator.relNumber == rewrite->new_locator.relNumber)
+			{
+				pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator);
+				goto found_entry;
+			}
+		}
+	}
+
 	/* Else find or make the PgStat_TableStatus entry, and update link */
-	rel->pgstat_info = pgstat_prep_relation_pending(locator);
+	pgstat_info = pgstat_prep_relation_pending(locator);
+
+found_entry:
+	rel->pgstat_info = pgstat_info;
+
+	/*
+	 * For relations stats, we key by physical file location, not by relation
+	 * OID. This means during operations like ALTER TYPE it's possible that
+	 * the relation OID changes but the relfilenode stays the same (no actual
+	 * rewrite needed). Unlink the old relation first.
+	 */
+	if (pgstat_info->relation != NULL &&
+		pgstat_info->relation != rel)
+	{
+		pgstat_info->relation->pgstat_info = NULL;
+		pgstat_info->relation = NULL;
+	}
 
 	/* don't allow link a stats to multiple relcache entries */
-	Assert(rel->pgstat_info->relation == NULL);
+	Assert(pgstat_info->relation == NULL);
 
 	/* mark this relation as the owner */
-	rel->pgstat_info->relation = rel;
+	pgstat_info->relation = rel;
 }
 
 /*
@@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel)
 {
 	int			nest_level = GetCurrentTransactionNestLevel();
 	PgStat_TableStatus *pgstat_info;
+	bool		skip_transactional_drop = false;
 
 	/* don't track stats for relations without storage */
 	if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
 		return;
 
-	pgstat_drop_transactional(PGSTAT_KIND_RELATION,
-							  rel->rd_locator.dbOid,
-							  RelFileLocatorToPgStatObjid(rel->rd_locator));
+	/* Check if this drop is part of a pending rewrite */
+	if (pending_rewrites != NULL)
+	{
+		PgStat_PendingRewrite *rewrite;
+
+		for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next)
+		{
+			if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid &&
+				rel->rd_locator.spcOid == rewrite->old_locator.spcOid &&
+				rel->rd_locator.relNumber == rewrite->old_locator.relNumber)
+			{
+				skip_transactional_drop = true;
+				break;
+			}
+		}
+	}
+
+	/*
+	 * If it is part of a rewrite, drop its stats later, for example in
+	 * AtEOXact_PgStat_Relations(), so skip it here.
+	 */
+	if (!skip_transactional_drop)
+		pgstat_drop_transactional(PGSTAT_KIND_RELATION,
+								  rel->rd_locator.dbOid,
+								  RelFileLocatorToPgStatObjid(rel->rd_locator));
 
 	if (!pgstat_should_count_relation(rel))
 		return;
@@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit)
 		}
 		tabstat->trans = NULL;
 	}
+
+	/* preserve the stats in case of rewrite */
+	if (isCommit && pending_rewrites != NULL)
+	{
+		PgStat_PendingRewrite *rewrite;
+		PgStat_PendingRewrite *prev = NULL;
+		PgStat_PendingRewrite *current = pending_rewrites;
+		PgStat_PendingRewrite *next;
+
+		/* reverse the rewrites list to process in chronological order */
+		while (current != NULL)
+		{
+			next = current->next;
+			current->next = prev;
+			prev = current;
+			current = next;
+		}
+
+		/* now process rewrites in chronological order */
+		for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next)
+		{
+			PgStat_EntryRef *old_entry_ref;
+
+			old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION,
+													   rewrite->old_locator.dbOid,
+													   RelFileLocatorToPgStatObjid(rewrite->old_locator));
+
+			if (old_entry_ref && old_entry_ref->pending)
+				pgstat_relation_flush_cb(old_entry_ref, false);
+
+			pgstat_copy_relation_stats(rewrite->new_locator,
+									   rewrite->old_locator, true);
+
+			/* drop old locator's stats */
+			if (!pgstat_drop_entry(PGSTAT_KIND_RELATION,
+								   rewrite->old_locator.dbOid,
+								   RelFileLocatorToPgStatObjid(rewrite->old_locator)))
+				pgstat_request_entry_refs_gc();
+		}
+	}
+
+	pending_rewrites = NULL;
 }
 
 /*
@@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in
 	PgStat_TableXactStatus *trans;
 	PgStat_TableXactStatus *next_trans;
 
+	/*
+	 * If we don't commit then remove the associated rewrites if any, to keep
+	 * the rewrite chain in sync with what will be eventually committed.
+	 */
+	if (!isCommit)
+	{
+		PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites;
+
+		while (*rewrite_ptr != NULL)
+		{
+			if ((*rewrite_ptr)->nest_level >= nestDepth)
+			{
+				PgStat_PendingRewrite *to_remove = *rewrite_ptr;
+
+				*rewrite_ptr = (*rewrite_ptr)->next;
+				pfree(to_remove);
+			}
+			else
+			{
+				rewrite_ptr = &((*rewrite_ptr)->next);
+			}
+		}
+	}
+
 	for (trans = xact_state->first; trans != NULL; trans = next_trans)
 	{
 		PgStat_TableStatus *tabstat;
@@ -754,11 +942,19 @@ void
 AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state)
 {
 	PgStat_TableXactStatus *trans;
+	PgStat_PendingRewrite *rewrite;
 
+	/*
+	 * For each tabstat, find its matching rewrite and remove it from the
+	 * pending rewrites list. This way, after processing all tabstats, pending
+	 * rewrites will only contain rewrite only transactions.
+	 */
 	for (trans = xact_state->first; trans != NULL; trans = trans->next)
 	{
 		PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY;
 		TwoPhasePgStatRecord record;
+		PgStat_PendingRewrite **rewrite_ptr;
+		bool		found_rewrite = false;
 
 		Assert(trans->nest_level == 1);
 		Assert(trans->upper == NULL);
@@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state)
 			record.locator = tabstat->locator;
 
 		record.truncdropped = trans->truncdropped;
+		record.rewrite_nest_level = 0;
+
+		/*
+		 * Look for a matching rewrite and remove it from pending rewrites. We
+		 * check three possible matches:
+		 *
+		 * The new_locator when stats have been added after the rewrite. The
+		 * old_locator when stats have been added before the rewrite but not
+		 * after. The original_locator when this tabstat is part of a rewrite
+		 * chain.
+		 */
+		rewrite_ptr = &pending_rewrites;
+		while (*rewrite_ptr != NULL)
+		{
+			rewrite = *rewrite_ptr;
+
+			if ((record.locator.dbOid == rewrite->new_locator.dbOid &&
+				 record.locator.spcOid == rewrite->new_locator.spcOid &&
+				 record.locator.relNumber == rewrite->new_locator.relNumber) ||
+				(tabstat->locator.dbOid == rewrite->old_locator.dbOid &&
+				 tabstat->locator.spcOid == rewrite->old_locator.spcOid &&
+				 tabstat->locator.relNumber == rewrite->old_locator.relNumber) ||
+				(tabstat->locator.dbOid == rewrite->original_locator.dbOid &&
+				 tabstat->locator.spcOid == rewrite->original_locator.spcOid &&
+				 tabstat->locator.relNumber == rewrite->original_locator.relNumber))
+			{
+				/*
+				 * Found matching rewrite. Record the rewrite information and
+				 * remove this rewrite from the list since it's now handled.
+				 */
+				record.rewrite_old_locator = rewrite->original_locator;
+				record.rewrite_nest_level = rewrite->nest_level;
+				record.locator = rewrite->new_locator;
+				found_rewrite = true;
+
+				/* Remove from pending_rewrites list */
+				*rewrite_ptr = rewrite->next;
+				pfree(rewrite);
+				break;
+			}
+			else
+			{
+				/* Move to next rewrite in the list */
+				rewrite_ptr = &(rewrite->next);
+			}
+		}
+
+		/* If no rewrite found, clear the rewrite fields */
+		if (!found_rewrite)
+		{
+			memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator));
+		}
+
+		RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0,
+							   &record, sizeof(TwoPhasePgStatRecord));
+	}
+
+	/*
+	 * Now process any rewrites still pending. These are rewrite only
+	 * transactions. We need to preserve their stats even though there's no
+	 * tabstat entry for them.
+	 */
+	for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next)
+	{
+		TwoPhasePgStatRecord record;
+
+		memset(&record, 0, sizeof(TwoPhasePgStatRecord));
+		record.locator = rewrite->new_locator;
+		record.rewrite_old_locator = rewrite->original_locator;
+		record.rewrite_nest_level = rewrite->nest_level;
+		record.truncdropped = false;
 
 		RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0,
 							   &record, sizeof(TwoPhasePgStatRecord));
 	}
+
+	pending_rewrites = NULL;
 }
 
 /*
@@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state)
 		tabstat = trans->parent;
 		tabstat->trans = NULL;
 	}
+
+	pending_rewrites = NULL;
 }
 
 /*
@@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info,
 	pgstat_info->counts.changed_tuples +=
 		rec->tuples_inserted + rec->tuples_updated +
 		rec->tuples_deleted;
+
+	if (rec->rewrite_nest_level > 0)
+	{
+		PgStat_EntryRef *old_entry_ref;
+
+		/* Flush any pending stats for old locator first */
+		old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION,
+												   rec->rewrite_old_locator.dbOid,
+												   RelFileLocatorToPgStatObjid(rec->rewrite_old_locator));
+
+		if (old_entry_ref && old_entry_ref->pending)
+			pgstat_relation_flush_cb(old_entry_ref, false);
+
+		/* Copy stats from old to new locator */
+		pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator,
+								   true);
+
+		/* Drop old locator's stats */
+		if (!pgstat_drop_entry(PGSTAT_KIND_RELATION,
+							   rec->rewrite_old_locator.dbOid,
+							   RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)))
+			pgstat_request_entry_refs_gc();
+	}
 }
 
 /*
@@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
 {
 	TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata;
 	PgStat_TableStatus *pgstat_info;
+	RelFileLocator target_locator;
+
+	/*
+	 * For aborted transactions with rewrites (like TRUNCATE), we need to
+	 * restore stats to the old locator, not the new one. The new locator
+	 * should be dropped since the rewrite is being rolled back.
+	 */
+	if (rec->rewrite_nest_level > 0)
+	{
+		/* Use the old locator */
+		target_locator = rec->rewrite_old_locator;
+	}
+	else
+	{
+		/* No rewrite, use the original locator */
+		target_locator = rec->locator;
+	}
 
 	/* Find or create a tabstat entry for the target locator */
-	pgstat_info = pgstat_prep_relation_pending(rec->locator);
+	pgstat_info = pgstat_prep_relation_pending(target_locator);
 
 	/* Same math as in AtEOXact_PgStat, abort case */
 	if (rec->truncdropped)
@@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
 	tabentry->numscans += lstats->counts.numscans;
 	if (lstats->counts.numscans)
 	{
-		TimestampTz t = GetCurrentTransactionStopTimestamp();
+		TimestampTz t;
+
+		/*
+		 * Checking the transaction state due to the flush call in
+		 * pgstat_twophase_postcommit() that would break the assertion on the
+		 * state in GetCurrentTransactionStopTimestamp().
+		 */
+		if (!IsTransactionState())
+			t = GetCurrentTransactionStopTimestamp();
+		else
+			t = GetCurrentTimestamp();
 
 		if (t > tabentry->lastscan)
 			tabentry->lastscan = t;
@@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator)
 	ReleaseSysCache(tuple);
 	return result;
 }
+
+/*
+ * Mark that a relation rewrite has occurred, preserving the original locator
+ * so stats can be copied at transaction commit.
+ */
+void
+pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator)
+{
+	PgStat_PendingRewrite *rewrite;
+	PgStat_PendingRewrite *existing;
+	RelFileLocator original_locator = old_locator;
+
+	for (existing = pending_rewrites; existing != NULL; existing = existing->next)
+	{
+		if (old_locator.dbOid == existing->new_locator.dbOid &&
+			old_locator.spcOid == existing->new_locator.spcOid &&
+			old_locator.relNumber == existing->new_locator.relNumber)
+		{
+			original_locator = existing->original_locator;
+			break;
+		}
+	}
+
+	/* Allocate in TopTransactionContext memory context */
+	rewrite = MemoryContextAlloc(TopTransactionContext,
+								 sizeof(PgStat_PendingRewrite));
+
+	rewrite->old_locator = old_locator;
+	rewrite->new_locator = new_locator;
+	rewrite->original_locator = original_locator;
+	rewrite->nest_level = GetCurrentTransactionNestLevel();
+
+	/* Add to the list */
+	rewrite->next = pending_rewrites;
+	pending_rewrites = rewrite;
+}
+
+void
+pgstat_clear_rewrite(void)
+{
+	pending_rewrites = NULL;
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..f8cf3755ce2 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	}
 	pgStatXactStack = NULL;
 
+	pgstat_clear_rewrite();
+
 	/* Make sure any stats snapshot is thrown away */
 	pgstat_clear_snapshot();
 }
@@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo
 void
 pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid)
 {
-	if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL))
+	PgStat_EntryRef *entry_ref;
+
+	entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL);
+
+	if (entry_ref)
 	{
+		/*
+		 * For relations stats, we key by physical file location, not by
+		 * relation OID. This means during operations like ALTER TYPE where
+		 * the relation OID changes but the relfilenode stays the same (no
+		 * actual rewrite needed), we'll find an existing entry.
+		 *
+		 * This is expected behavior, we want to preserve stats across the
+		 * catalog change. Simply reset and recreate the entry for the new
+		 * relation OID without warning.
+		 */
+		if (kind == PGSTAT_KIND_RELATION)
+		{
+			pgstat_reset(kind, dboid, objid);
+			create_drop_transactional_internal(kind, dboid, objid, true);
+			return;
+		}
+
 		ereport(WARNING,
 				errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64,
 					   (pgstat_get_kind_info(kind))->name, dboid,
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 915d0bc9084..7a7f8023eb3 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -85,6 +85,7 @@
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
+#include "utils/pgstat_internal.h"
 #include "utils/relmapper.h"
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
@@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence)
 	MultiXactId minmulti = InvalidMultiXactId;
 	TransactionId freezeXid = InvalidTransactionId;
 	RelFileLocator newrlocator;
+	RelFileLocator oldrlocator = relation->rd_locator;
 
 	if (!IsBinaryUpgrade)
 	{
@@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence)
 
 	table_close(pg_class, RowExclusiveLock);
 
+	/* Mark that a rewrite happened */
+	if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind))
+		pgstat_mark_rewrite(oldrlocator, newrlocator);
+
 	/*
 	 * Make the pg_class row change or relation map change visible.  This will
 	 * cause the relcache entry to get updated, too.
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d0fe79f7e3..332dffde400 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id);
 
 extern void pgstat_create_relation(Relation rel);
 extern void pgstat_drop_relation(Relation rel);
-extern void pgstat_copy_relation_stats(Relation dst, Relation src);
+extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment);
 
 extern void pgstat_init_relation(Relation rel);
 extern void pgstat_assoc_relation(Relation rel);
@@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl
 extern void pgstat_report_analyze(Relation rel,
 								  PgStat_Counter livetuples, PgStat_Counter deadtuples,
 								  bool resetcounter, TimestampTz starttime);
+extern void pgstat_mark_rewrite(RelFileLocator old_locator,
+								RelFileLocator new_locator);
+extern void pgstat_clear_rewrite(void);
 
 /*
  * If stats are enabled, but pending data hasn't been prepared yet, call
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 432509277c9..bd8fcb16dcf 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2248,6 +2248,7 @@ PgStat_KindInfo
 PgStat_LocalState
 PgStat_PendingDroppedStatsItem
 PgStat_PendingIO
+PgStat_PendingRewrite
 PgStat_SLRUStats
 PgStat_ShmemControl
 PgStat_Snapshot
-- 
2.34.1

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  To: pgsql-hackers@postgresql.org
  Cc: bertranddrouvot.pg@gmail.com, michael@paquier.xyz, reshkekirill@gmail.com, robertmhaas@gmail.com, pgsql-hackers@lists.postgresql.org
  Subject: Re: relfilenode statistics
  In-Reply-To: <aQ3X20hbqoThQXgp@ip-10-97-1-34.eu-west-3.compute.internal>

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