Subject: Report index currently being vacuumed in pg_stat_progress_vacuum

From: Bharath Rupireddy <[email-masked]>
Date: Sun, 3 May 2026 19:00:00 -0700

Hi,

When VACUUM is in the "vacuuming indexes" or "cleaning up indexes" phase,
there is currently no easy way to tell which specific index is being
processed. The progress report view shows indexes_total and
indexes_processed counters, but not which index is actively being worked on.

This makes it difficult to debug slow or stuck autovacuum workers on tables
with multiple indexes of different types (btree, GIN, GiST, BRIN, HNSW,
etc.), since one cannot determine which index type or which specific index
is causing the delay.

Please find the attached patch adds a new column current_index_relid to
pg_stat_progress_vacuum that reports the OID of the index currently being
vacuumed or cleaned up. The column is reported for both the "vacuuming
indexes" phase and the "cleaning up indexes" phase.

When indexes are being vacuumed in parallel, each parallel worker emits its
own row in pg_stat_progress_vacuum with current_index_relid set to the
index it is currently processing, and leader_pid pointing to the leader
process.

Appreciate any feedback. Thank you!

[1] Example output:

 pid  | datname  | relid | table_name |       phase       | started_by |
current_index_relid |  index_name   | leader_pid
------+----------+-------+------------+-------------------+------------+---------------------+---------------+------------
 1420 | postgres | 16395 | vac_test   | vacuuming indexes | autovacuum |
            16398 | vac_test_idx1 |
 1421 | postgres | 16395 | vac_test   | vacuuming indexes |            |
            16399 | vac_test_idx2 |       1420
 1423 | postgres | 16395 | vac_test   | vacuuming indexes |            |
            16400 | vac_test_idx3 |       1420
(3 rows)

 pid  | datname  | relid | table_name |       phase       | started_by |
current_index_relid |  index_name   | leader_pid
------+----------+-------+------------+-------------------+------------+---------------------+---------------+------------
 1346 | postgres | 16395 | vac_test   | vacuuming indexes | manual     |
            16398 | vac_test_idx1 |
(1 row)

[2]
SELECT v.pid, v.datname, v.relid, c.relname AS table_name,
       v.phase, v.started_by, v.current_index_relid,
       COALESCE(ic.relname, '') AS index_name, v.leader_pid
FROM pg_stat_progress_vacuum v
JOIN pg_class c
    ON c.oid = v.relid
LEFT JOIN pg_class ic
    ON ic.oid = v.current_index_relid
WHERE v.relid = $tbl_oid
ORDER BY
    v.leader_pid,
    v.pid;

-- 
Bharath Rupireddy
Amazon Web Services: https://aws.amazon.com

---

From: SATYANARAYANA NARLAPURAM <[email-masked]>
Date: Sun, 3 May 2026 21:53:04 -0700

Hi,

On Sun, May 3, 2026 at 7:01 PM Bharath Rupireddy <
[email-masked]> wrote:

> This makes it difficult to debug slow or stuck autovacuum workers on
> tables with multiple indexes of different types (btree, GIN, GiST, BRIN,
> HNSW, etc.), since one cannot determine which index type or which specific
> index is causing the delay.
>
> When indexes are being vacuumed in parallel, each parallel worker emits
> its own row in pg_stat_progress_vacuum with current_index_relid set to the

Bharath, thanks for the patch! A few comments:

 (1) Do we need a global API? Can we add a leader_pid field in PVShared?

+pid_t
+GetParallelLeaderPid(void)
+{
+ return ParallelLeaderPid;
+}

(2):  Looks like current_index_relid is not cleared when we leave the index
phases.As a result, once any index has been processed,
pg_stat_progress_vacuum.current_index_relid keeps reporting that relid
through vacuuming heap, truncating heap, cleaning up indexes.
This will be confusing to the user. Something like below:

1795819|vacuuming heap|0/0|16392|t1_pkey|LEADER

(3) leader_pid type should be integer type similar to pg_Stat_activity?

Thanks,
Satya

---

From: Antonin Houska <[email-masked]>
Date: Mon, 04 May 2026 11:52:13 +0200

Bharath Rupireddy <[email-masked]> wrote:

> When VACUUM is in the "vacuuming indexes" or "cleaning up indexes" phase, there is currently no easy way to tell which specific index is
> being processed. The progress report view shows indexes_total and indexes_processed counters, but not which index is actively being worked
> on.
> 
> This makes it difficult to debug slow or stuck autovacuum workers on tables with multiple indexes of different types (btree, GIN, GiST, BRIN,
> HNSW, etc.), since one cannot determine which index type or which specific index is causing the delay.
> 
> Please find the attached patch adds a new column current_index_relid to pg_stat_progress_vacuum that reports the OID of the index
> currently being vacuumed or cleaned up. The column is reported for both the "vacuuming indexes" phase and the "cleaning up indexes"
> phase.
> 
> When indexes are being vacuumed in parallel, each parallel worker emits its own row in pg_stat_progress_vacuum with current_index_relid
> set to the index it is currently processing, and leader_pid pointing to the leader process.
> 

This problem seems to be similar to what I noticed when workign on the REPACK
command: progress reporting of index build needs to be disabled if the build
is part of REPACK, otherwise the index build can overwrite the counters of
REPACK (whether the overwriting actually happens or not is another question).

The solution I suggest is to allow progress tracking of a "sub-command" - see
the attached patch. Wouldn't that also resolve your problem? (My plan is to
incorporate this in the series of REPACK enhancements soon.)

-- 
Antonin Houska
Web: https://www.cybertec-postgresql.com

---

From: Sami Imseih <[email-masked]>
Date: Tue, 5 May 2026 12:54:25 -0500

Hi,

> Appreciate any feedback. Thank you!

I think it is valuable to show the index being processed. There is
really no other easy way to get this information except for pstack,
etc. I am +1 for the idea.

However, I am not sure that having a separate row for every parallel
worker is the right approach. The pg_stat_progress_* views are designed
to show progress per row. Each row represents one command with
meaningful progress counters (heap_blks_scanned, indexes_total,
indexes_processed, etc.). A parallel worker row would only show
current_index_relid and leader_pid with no actual progress information
of its own. That is status, not progress, and it does not fit the
view. Also, many columns would remain empty or redundant with the
leader's row.

Instead, could we  aggregate the parallel worker information into the
leader's row. For example, an array of worker PIDs in one column and an
array of index relids in another?

--
Sami Imseih
Amazon Web Services (AWS)

---

From: Bharath Rupireddy <[email-masked]>
Date: Mon, 29 Jun 2026 08:31:12 -0700

Hi,

> etc. I am +1 for the idea.

Thanks for reviewing this!

> array of index relids in another?

Thanks for the review. I read f1889729 and it looks like the
preference was to keep one command = one row, with workers feeding the
leader's row rather than showing up as separate rows. I want to stay
with that approach.

I considered having the leader set up a DSA that workers write into,
shown as an extra column on the leader's row. But that means new
shared memory whose handle has to be stored somewhere other backends
can find it, attached by the reader, and freed safely while a
monitoring query might still be reading it - that's a lot of work for
a small amount of per-worker data.

The simpler approach is to have workers report the index they're
currently on into their own st_progress_param[] slots, which already
exist per backend, along with their leader's pid. The view then groups
the worker entries under the matching leader's pid and shows only the
leader rows, so no new shared memory is needed. The current index oid
column has to be added to that array anyway for the non-parallel case,
which needs it just as much, and the parallel workers already have
their own slots to report into, so there's nothing extra to set up.
One thing to note is that pg_stat_get_progress_info('VACUUM') itself
would still return the worker rows, and the grouping happens in the
pg_stat_progress_vacuum view instead. I prefer keeping it in the view
rather than the function. The function is shared by all the progress
commands and only deals with raw params, while the leader pid grouping
is specific to VACUUM. This way the shared function stays unchanged
and the other progress views are not affected.

While I'm here, in the "vacuuming indexes" phase I also want to report
the total index pages to scan and the pages scanned so far, for the
index currently being vacuumed. On a large index this phase can run
for a long time with no way to tell whether it's making progress.

Does this direction sound reasonable, or do you see a reason to prefer
a different approach?