Date: Wed, 5 Mar 2025 07:17:09 +0000
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Peter Smith <smithpb2250@gmail.com>,
	Peter Eisentraut <peter@eisentraut.org>,
	shveta malik <shveta.malik@gmail.com>,
	Amit Kapila <amit.kapila16@gmail.com>,
	Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: Add contrib/pg_logicalsnapinspect
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Hi,

On Tue, Mar 04, 2025 at 10:25:57PM -0800, Masahiko Sawada wrote:
> On Tue, Mar 4, 2025 at 1:56 PM Andres Freund <andres@anarazel.de> wrote:
> >
> Thank you for the report.

+1

> It seems that bgwriter wrote another RUNNING_XACTS record during the
> test, making the logical decoding write an extra snapshot on the disk.

Yup.

> One way to stabilize the regression test would be that we check if
> there is a serialized snapshot that has expected number of catchange
> transactions and number of committed transactions, instead of dumping
> all serialized snapshots.

Agree, PFA a patch doing so.

Regards,

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

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	filename="v1-0001-Modify-pg_logicalinspect-isolation-test.patch"

From d590d3184d4345908f1b033aa8a5d19cf98e88ba Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Date: Wed, 5 Mar 2025 07:06:58 +0000
Subject: [PATCH v1] Modify pg_logicalinspect isolation test

The previous version was relying on the fact that the test produces exactly
2 snapshots on disk, while in fact it can produce more. Changing the test knowing
that at least 2 snapshots are generated.

Per buildfarm member skink.
---
 .../expected/logical_inspect.out              | 29 +++++++++++--------
 .../specs/logical_inspect.spec                |  7 +++--
 2 files changed, 21 insertions(+), 15 deletions(-)
  57.3% contrib/pg_logicalinspect/expected/
  42.6% contrib/pg_logicalinspect/specs/

diff --git a/contrib/pg_logicalinspect/expected/logical_inspect.out b/contrib/pg_logicalinspect/expected/logical_inspect.out
index d95efa4d1e5..ecba05b9ab1 100644
--- a/contrib/pg_logicalinspect/expected/logical_inspect.out
+++ b/contrib/pg_logicalinspect/expected/logical_inspect.out
@@ -1,6 +1,6 @@
 Parsed test spec with 2 sessions
 
-starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes s1_get_logical_snapshot_info s1_get_logical_snapshot_meta
+starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes s1_get_logical_snapshot_info_catchange s1_get_logical_snapshot_info_committed s1_get_logical_snapshot_meta
 step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
 ?column?
 --------
@@ -37,16 +37,21 @@ table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
 COMMIT                                                       
 (3 rows)
 
-step s1_get_logical_snapshot_info: SELECT info.state, info.catchange_count, array_length(info.catchange_xip,1) AS catchange_array_length, info.committed_count, array_length(info.committed_xip,1) AS committed_array_length FROM pg_ls_logicalsnapdir(), pg_get_logical_snapshot_info(name) AS info ORDER BY 2;
-state     |catchange_count|catchange_array_length|committed_count|committed_array_length
-----------+---------------+----------------------+---------------+----------------------
-consistent|              0|                      |              2|                     2
-consistent|              2|                     2|              0|                      
-(2 rows)
-
-step s1_get_logical_snapshot_meta: SELECT COUNT(meta.*) from pg_ls_logicalsnapdir(), pg_get_logical_snapshot_meta(name) as meta;
-count
------
-    2
+step s1_get_logical_snapshot_info_catchange: SELECT count(*) > 0 as has_catchange FROM pg_ls_logicalsnapdir(), pg_get_logical_snapshot_info(name) AS info where info.catchange_count = 2 and array_length(info.catchange_xip,1) = 2 and info.committed_count = 0;
+has_catchange
+-------------
+t            
+(1 row)
+
+step s1_get_logical_snapshot_info_committed: SELECT count(*) > 0 as has_committed FROM pg_ls_logicalsnapdir(), pg_get_logical_snapshot_info(name) AS info where info.committed_count = 2 and array_length(info.committed_xip,1) = 2 and info.catchange_count = 0;
+has_committed
+-------------
+t            
+(1 row)
+
+step s1_get_logical_snapshot_meta: SELECT COUNT(meta.*) > 1 AS has_meta from pg_ls_logicalsnapdir(), pg_get_logical_snapshot_meta(name) as meta;
+has_meta
+--------
+t       
 (1 row)
 
diff --git a/contrib/pg_logicalinspect/specs/logical_inspect.spec b/contrib/pg_logicalinspect/specs/logical_inspect.spec
index 9851a6c18e4..673d2f5ed0a 100644
--- a/contrib/pg_logicalinspect/specs/logical_inspect.spec
+++ b/contrib/pg_logicalinspect/specs/logical_inspect.spec
@@ -28,7 +28,8 @@ session "s1"
 setup { SET synchronous_commit=on; }
 step "s1_checkpoint" { CHECKPOINT; }
 step "s1_get_changes" { SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
-step "s1_get_logical_snapshot_meta" { SELECT COUNT(meta.*) from pg_ls_logicalsnapdir(), pg_get_logical_snapshot_meta(name) as meta;}
-step "s1_get_logical_snapshot_info" { SELECT info.state, info.catchange_count, array_length(info.catchange_xip,1) AS catchange_array_length, info.committed_count, array_length(info.committed_xip,1) AS committed_array_length FROM pg_ls_logicalsnapdir(), pg_get_logical_snapshot_info(name) AS info ORDER BY 2; }
+step "s1_get_logical_snapshot_meta" { SELECT COUNT(meta.*) > 1 AS has_meta from pg_ls_logicalsnapdir(), pg_get_logical_snapshot_meta(name) as meta; }
+step "s1_get_logical_snapshot_info_catchange" { SELECT count(*) > 0 as has_catchange FROM pg_ls_logicalsnapdir(), pg_get_logical_snapshot_info(name) AS info where info.catchange_count = 2 and array_length(info.catchange_xip,1) = 2 and info.committed_count = 0; }
+step "s1_get_logical_snapshot_info_committed" { SELECT count(*) > 0 as has_committed FROM pg_ls_logicalsnapdir(), pg_get_logical_snapshot_info(name) AS info where info.committed_count = 2 and array_length(info.committed_xip,1) = 2 and info.catchange_count = 0; }
 
-permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes" "s1_get_logical_snapshot_info" "s1_get_logical_snapshot_meta"
+permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes" "s1_get_logical_snapshot_info_catchange" "s1_get_logical_snapshot_info_committed" "s1_get_logical_snapshot_meta"
-- 
2.34.1


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