Hi Amit,
Thanks for reviewing the patch.

On Thu, 23 Oct 2025 at 16:58, Amit Kapila <[email protected]> wrote:
>
> On Thu, Oct 23, 2025 at 2:58 PM Shlok Kyal <[email protected]> wrote:
> >
> > On Thu, 23 Oct 2025 at 13:45, Hayato Kuroda (Fujitsu)
> > <[email protected]> wrote:
> > >
> > > 2.
> > > Also, test for PG18 should not have the case which rejects the reserved 
> > > name.
> > >
>
> Why to have that even for HEAD and PG18?
>
I added it as per comment in [1] to increase test coverage. I also do
not see any other existing test in HEAD hitting this error. So I added
this test.

> > > 3.
> > > ```
> > > -- Parallel worker does not throw error during startup.
> > > SET min_parallel_table_scan_size TO 0;
> > > SET parallel_setup_cost TO 0;
> > > SET parallel_tuple_cost TO 0;
> > > ```
> > >
> > > According to contrib/pg_stat_statements/sql/parallel.sql, 
> > > max_parallel_workers_per_gather
> > > should be also set. There is a possiblity that `make installcheck` is 
> > > used and
> > > it has max_parallel_workers_per_gather=0.
> > >
>
> +-- Parallel worker does not throw error during startup.
> +SET min_parallel_table_scan_size TO 0;
> +SET max_parallel_workers_per_gather TO 2;
> +SET parallel_setup_cost TO 0;
> +SET parallel_tuple_cost TO 0;
> +CREATE TABLE t1(a int);
> +INSERT INTO t1 VALUES(1), (2), (3), (4);
> +SELECT count(*) FROM t1;
>
> Isn't it better to reset these parameters after the test?
>
According to the latest discussion. I have removed this test.
Attached the updated patches.

[1]: 
https://www.postgresql.org/message-id/CAE9k0P%3DOFMFCRy9aDGWZ3bt91tbB1WnzsAbzXN72iWBaGVuMrw%40mail.gmail.com

Thanks,
Shlok Kyal
From 628373744030d102d41391c2838d3ab4a15bd343 Mon Sep 17 00:00:00 2001
From: Shlok Kyal <[email protected]>
Date: Thu, 23 Oct 2025 11:09:47 +0530
Subject: [PATCH v8_REL_17] Remove the validation from the GUC check hook and
 add parsing check

The validation in check_synchronized_standby_slots cannot be run
in postmaster and hence can result inconsistent values in some
backends that inherit the value from postmaster and those
that are started newly. Also, this validation results in parallel
workers fail to with error. This causes all the commands run by
parallel workers to fail, which seems unnecesary. This validation
already happens in StandbySlotsHaveCaughtup() where this GUC is
used, so it can be removed from the GUC check. Also added a
parsing check for the slot names specified in this GUC.
---
 src/backend/replication/slot.c    | 59 +++++++++----------------------
 src/test/regress/expected/guc.out | 22 ++++++++++++
 src/test/regress/sql/guc.sql      | 12 +++++++
 3 files changed, 50 insertions(+), 43 deletions(-)

diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 80b8abde3a2..4bc2be33396 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -2468,53 +2468,32 @@ GetSlotInvalidationCause(const char 
*invalidation_reason)
 static bool
 validate_sync_standby_slots(char *rawname, List **elemlist)
 {
-       bool            ok;
-
        /* Verify syntax and parse string into a list of identifiers */
-       ok = SplitIdentifierString(rawname, ',', elemlist);
-
-       if (!ok)
+       if (!SplitIdentifierString(rawname, ',', elemlist))
        {
                GUC_check_errdetail("List syntax is invalid.");
+               return false;
        }
-       else if (MyProc)
+
+       /* Iterate the list to validate each slot name */
+       foreach_ptr(char, name, *elemlist)
        {
-               /*
-                * Check that each specified slot exist and is physical.
-                *
-                * Because we need an LWLock, we cannot do this on processes 
without a
-                * PGPROC, so we skip it there; but see comments in
-                * StandbySlotsHaveCaughtup() as to why that's not a problem.
-                */
-               LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
+               int                     err_code;
+               char       *err_msg = NULL;
+               char       *err_hint = NULL;
 
-               foreach_ptr(char, name, *elemlist)
+               if (!ReplicationSlotValidateNameInternal(name, &err_code, 
&err_msg,
+                                                                               
                 &err_hint))
                {
-                       ReplicationSlot *slot;
-
-                       slot = SearchNamedReplicationSlot(name, false);
-
-                       if (!slot)
-                       {
-                               GUC_check_errdetail("replication slot \"%s\" 
does not exist",
-                                                                       name);
-                               ok = false;
-                               break;
-                       }
-
-                       if (!SlotIsPhysical(slot))
-                       {
-                               GUC_check_errdetail("\"%s\" is not a physical 
replication slot",
-                                                                       name);
-                               ok = false;
-                               break;
-                       }
+                       GUC_check_errcode(err_code);
+                       GUC_check_errdetail("%s", err_msg);
+                       if (err_hint != NULL)
+                               GUC_check_errhint("%s", err_hint);
+                       return false;
                }
-
-               LWLockRelease(ReplicationSlotControlLock);
        }
 
-       return ok;
+       return true;
 }
 
 /*
@@ -2672,12 +2651,6 @@ StandbySlotsHaveCaughtup(XLogRecPtr wait_for_lsn, int 
elevel)
                /*
                 * If a slot name provided in synchronized_standby_slots does 
not
                 * exist, report a message and exit the loop.
-                *
-                * Though validate_sync_standby_slots (the GUC check_hook) 
tries to
-                * avoid this, it can nonetheless happen because the user can 
specify
-                * a nonexistent slot name before server startup. That function 
cannot
-                * validate such a slot during startup, as ReplicationSlotCtl 
is not
-                * initialized by then.  Also, the user might have dropped one 
slot.
                 */
                if (!slot)
                {
diff --git a/src/test/regress/expected/guc.out 
b/src/test/regress/expected/guc.out
index 455b6d6c0ce..f6bf9238b4a 100644
--- a/src/test/regress/expected/guc.out
+++ b/src/test/regress/expected/guc.out
@@ -888,3 +888,25 @@ SELECT name FROM tab_settings_flags
 (0 rows)
 
 DROP TABLE tab_settings_flags;
+-- Test for GUC synchronized standby slots.
+-- Cannot set synchronized_standby_slots to an invalid slot name.
+ALTER SYSTEM SET synchronized_standby_slots='invalid*';
+ERROR:  invalid value for parameter "synchronized_standby_slots": "invalid*"
+DETAIL:  replication slot name "invalid*" contains invalid character
+HINT:  Replication slot names may only contain lower case letters, numbers, 
and the underscore character.
+-- Can set synchronized_standby_slots to a non-existent slot name.
+ALTER SYSTEM SET synchronized_standby_slots='missing';
+SELECT pg_reload_conf();
+ pg_reload_conf 
+----------------
+ t
+(1 row)
+
+-- Reset the GUC.
+ALTER SYSTEM RESET synchronized_standby_slots;
+SELECT pg_reload_conf();
+ pg_reload_conf 
+----------------
+ t
+(1 row)
+
diff --git a/src/test/regress/sql/guc.sql b/src/test/regress/sql/guc.sql
index dc79761955d..5a2b6ed596c 100644
--- a/src/test/regress/sql/guc.sql
+++ b/src/test/regress/sql/guc.sql
@@ -353,3 +353,15 @@ SELECT name FROM tab_settings_flags
   WHERE no_reset AND NOT no_reset_all
   ORDER BY 1;
 DROP TABLE tab_settings_flags;
+
+-- Test for GUC synchronized standby slots.
+-- Cannot set synchronized_standby_slots to an invalid slot name.
+ALTER SYSTEM SET synchronized_standby_slots='invalid*';
+
+-- Can set synchronized_standby_slots to a non-existent slot name.
+ALTER SYSTEM SET synchronized_standby_slots='missing';
+SELECT pg_reload_conf();
+
+-- Reset the GUC.
+ALTER SYSTEM RESET synchronized_standby_slots;
+SELECT pg_reload_conf();
-- 
2.34.1

From b29d4c75463d2b8fafb4a3cc656156b5abf7194d Mon Sep 17 00:00:00 2001
From: Shlok Kyal <[email protected]>
Date: Wed, 10 Sep 2025 15:08:23 +0530
Subject: [PATCH v8_REL_18] Remove the validation from the GUC check hook and
 add parsing check

The validation in check_synchronized_standby_slots cannot be run
in postmaster and hence can result inconsistent values in some
backends that inherit the value from postmaster and those
that are started newly. Also, this validation results in parallel
workers fail to with error. This causes all the commands run by
parallel workers to fail, which seems unnecesary. This validation
already happens in StandbySlotsHaveCaughtup() where this GUC is
used, so it can be removed from the GUC check. Also added a
parsing check for the slot names specified in this GUC.
---
 src/backend/replication/slot.c    | 59 +++++++++----------------------
 src/test/regress/expected/guc.out | 22 ++++++++++++
 src/test/regress/sql/guc.sql      | 12 +++++++
 3 files changed, 50 insertions(+), 43 deletions(-)

diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index ac910f6a74a..101157ed8c9 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -2743,53 +2743,32 @@ 
GetSlotInvalidationCauseName(ReplicationSlotInvalidationCause cause)
 static bool
 validate_sync_standby_slots(char *rawname, List **elemlist)
 {
-       bool            ok;
-
        /* Verify syntax and parse string into a list of identifiers */
-       ok = SplitIdentifierString(rawname, ',', elemlist);
-
-       if (!ok)
+       if (!SplitIdentifierString(rawname, ',', elemlist))
        {
                GUC_check_errdetail("List syntax is invalid.");
+               return false;
        }
-       else if (MyProc)
+
+       /* Iterate the list to validate each slot name */
+       foreach_ptr(char, name, *elemlist)
        {
-               /*
-                * Check that each specified slot exist and is physical.
-                *
-                * Because we need an LWLock, we cannot do this on processes 
without a
-                * PGPROC, so we skip it there; but see comments in
-                * StandbySlotsHaveCaughtup() as to why that's not a problem.
-                */
-               LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
+               int                     err_code;
+               char       *err_msg = NULL;
+               char       *err_hint = NULL;
 
-               foreach_ptr(char, name, *elemlist)
+               if (!ReplicationSlotValidateNameInternal(name, &err_code, 
&err_msg,
+                                                                               
                 &err_hint))
                {
-                       ReplicationSlot *slot;
-
-                       slot = SearchNamedReplicationSlot(name, false);
-
-                       if (!slot)
-                       {
-                               GUC_check_errdetail("Replication slot \"%s\" 
does not exist.",
-                                                                       name);
-                               ok = false;
-                               break;
-                       }
-
-                       if (!SlotIsPhysical(slot))
-                       {
-                               GUC_check_errdetail("\"%s\" is not a physical 
replication slot.",
-                                                                       name);
-                               ok = false;
-                               break;
-                       }
+                       GUC_check_errcode(err_code);
+                       GUC_check_errdetail("%s", err_msg);
+                       if (err_hint != NULL)
+                               GUC_check_errhint("%s", err_hint);
+                       return false;
                }
-
-               LWLockRelease(ReplicationSlotControlLock);
        }
 
-       return ok;
+       return true;
 }
 
 /*
@@ -2947,12 +2926,6 @@ StandbySlotsHaveCaughtup(XLogRecPtr wait_for_lsn, int 
elevel)
                /*
                 * If a slot name provided in synchronized_standby_slots does 
not
                 * exist, report a message and exit the loop.
-                *
-                * Though validate_sync_standby_slots (the GUC check_hook) 
tries to
-                * avoid this, it can nonetheless happen because the user can 
specify
-                * a nonexistent slot name before server startup. That function 
cannot
-                * validate such a slot during startup, as ReplicationSlotCtl 
is not
-                * initialized by then.  Also, the user might have dropped one 
slot.
                 */
                if (!slot)
                {
diff --git a/src/test/regress/expected/guc.out 
b/src/test/regress/expected/guc.out
index 7f9e29c765c..6e9a635647d 100644
--- a/src/test/regress/expected/guc.out
+++ b/src/test/regress/expected/guc.out
@@ -913,3 +913,25 @@ SELECT name FROM tab_settings_flags
 (0 rows)
 
 DROP TABLE tab_settings_flags;
+-- Test for GUC synchronized standby slots.
+-- Cannot set synchronized_standby_slots to an invalid slot name.
+ALTER SYSTEM SET synchronized_standby_slots='invalid*';
+ERROR:  invalid value for parameter "synchronized_standby_slots": "invalid*"
+DETAIL:  replication slot name "invalid*" contains invalid character
+HINT:  Replication slot names may only contain lower case letters, numbers, 
and the underscore character.
+-- Can set synchronized_standby_slots to a non-existent slot name.
+ALTER SYSTEM SET synchronized_standby_slots='missing';
+SELECT pg_reload_conf();
+ pg_reload_conf 
+----------------
+ t
+(1 row)
+
+-- Reset the GUC.
+ALTER SYSTEM RESET synchronized_standby_slots;
+SELECT pg_reload_conf();
+ pg_reload_conf 
+----------------
+ t
+(1 row)
+
diff --git a/src/test/regress/sql/guc.sql b/src/test/regress/sql/guc.sql
index f65f84a2632..1f3324932c2 100644
--- a/src/test/regress/sql/guc.sql
+++ b/src/test/regress/sql/guc.sql
@@ -368,3 +368,15 @@ SELECT name FROM tab_settings_flags
   WHERE no_reset AND NOT no_reset_all
   ORDER BY 1;
 DROP TABLE tab_settings_flags;
+
+-- Test for GUC synchronized standby slots.
+-- Cannot set synchronized_standby_slots to an invalid slot name.
+ALTER SYSTEM SET synchronized_standby_slots='invalid*';
+
+-- Can set synchronized_standby_slots to a non-existent slot name.
+ALTER SYSTEM SET synchronized_standby_slots='missing';
+SELECT pg_reload_conf();
+
+-- Reset the GUC.
+ALTER SYSTEM RESET synchronized_standby_slots;
+SELECT pg_reload_conf();
-- 
2.34.1

Attachment: v8_HEAD-0001-Remove-the-validation-from-the-GUC-check-hoo.patch
Description: Binary data

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