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help / color / mirror / Atom feedFrom: Fujii Masao <[email protected]>
To: PostgreSQL Hackers <[email protected]>
Subject: Fix pg_stat_progress_data_checksums counter initialization
Date: Fri, 10 Jul 2026 16:13:56 +0900
Message-ID: <CAHGQGwEOQyEzW2cqrHEzvwbcsAsuH8MEe7MMidFOFxECy0E1_Q@mail.gmail.com> (raw)
Hi,
The pg_stat_progress_data_checksums docs says that databases_total and
databases_done are reported as NULL for workers, but I observed that
they are reported as 0 instead:
=# select * from pg_stat_progress_data_checksums;
pid | datid | datname | phase | databases_total |
databases_done | relations_total | relations_done | blocks_total |
blocks_done
-------+-------+----------+----------+-----------------+----------------+-----------------+----------------+--------------+-------------
34873 | 0 | (null) | enabling | 3 |
0 | (null) | (null) | (null) | (null)
34874 | 5 | postgres | enabling | 0 |
0 | 297 | 0 | 163935 | 427
(2 rows)
The cause is that pg_stat_progress_data_checksums uses -1 as the
sentinel value displayed as NULL, but pgstat_progress_start_command()
initializes all progress counters to zero. Data checksum progress did not
consistently reset those counters to -1, so some counters could
incorrectly appear as 0 instead of NULL.
The attached patch fixes this by initializing all data checksum progress
counters to -1 immediately after progress reporting starts for both
launcher and worker processes.
While looking at this code, I also found that blocks_done is not reset
when a worker starts processing a new relation fork. As a result,
blocks_done can temporarily exceed blocks_total, or a stale blocks_done
value can remain visible for an empty relation fork. The attached patch
resets blocks_done together with blocks_total when starting each
relation fork.
Regards,
--
Fujii Masao
Attachments:
[application/octet-stream] v1-0001-Fix-data-checksum-progress-counter-initialization.patch (7.2K, ../CAHGQGwEOQyEzW2cqrHEzvwbcsAsuH8MEe7MMidFOFxECy0E1_Q@mail.gmail.com/2-v1-0001-Fix-data-checksum-progress-counter-initialization.patch)
download | inline diff:
From 778b500c246c410ea4726383db965ec0b3d10a71 Mon Sep 17 00:00:00 2001
From: Fujii Masao <[email protected]>
Date: Fri, 10 Jul 2026 15:15:24 +0900
Subject: [PATCH v1] Fix data checksum progress counter initialization
pg_stat_progress_data_checksums uses -1 as a sentinel value that is
displayed as NULL for progress counters. However, after
pgstat_progress_start_command() initialized all progress counters to
zero, data checksum progress did not reset those counters to -1.
As a result, some counters could incorrectly appear as zero instead
of NULL. For example, workers could report zero database counters,
and the disabling launcher could report zero relation and block counters.
Also, blocks_done was not reset when a worker started processing
a new relation fork. As a result, it could temporarily exceed blocks_total
or report a stale value for an empty relation fork.
Fix this by initializing the data checksum progress counters to -1
when progress reporting starts for both launcher and worker processes.
Also reset blocks_done together with blocks_total when starting each
relation fork.
---
doc/src/sgml/monitoring.sgml | 8 ++--
src/backend/catalog/system_views.sql | 2 +-
src/backend/postmaster/datachecksum_state.c | 53 ++++++++++++++++-----
src/test/regress/expected/rules.out | 5 +-
4 files changed, 50 insertions(+), 18 deletions(-)
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 858788b227c..d1a20d001e9 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -8095,8 +8095,8 @@ FROM pg_stat_get_backend_idset() AS backendid;
</para>
<para>
The total number of databases which will be processed. Only the
- launcher process has this value set, the worker processes have this
- set to <literal>NULL</literal>.
+ launcher process has this value set when enabling data checksums;
+ otherwise this is set to <literal>NULL</literal>.
</para>
</entry>
</row>
@@ -8108,8 +8108,8 @@ FROM pg_stat_get_backend_idset() AS backendid;
</para>
<para>
The number of databases which have been processed. Only the launcher
- process has this value set, the worker processes have this set to
- <literal>NULL</literal>.
+ process has this value set when enabling data checksums; otherwise
+ this is set to <literal>NULL</literal>.
</para>
</entry>
</row>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 6c1c5545cb5..090281a03dd 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1493,7 +1493,7 @@ CREATE VIEW pg_stat_progress_data_checksums AS
WHEN 4 THEN 'done'
END AS phase,
CASE S.param2 WHEN -1 THEN NULL ELSE S.param2 END AS databases_total,
- S.param3 AS databases_done,
+ CASE S.param3 WHEN -1 THEN NULL ELSE S.param3 END AS databases_done,
CASE S.param4 WHEN -1 THEN NULL ELSE S.param4 END AS relations_total,
CASE S.param5 WHEN -1 THEN NULL ELSE S.param5 END AS relations_done,
CASE S.param6 WHEN -1 THEN NULL ELSE S.param6 END AS blocks_total,
diff --git a/src/backend/postmaster/datachecksum_state.c b/src/backend/postmaster/datachecksum_state.c
index 68557c16cb9..bec110105df 100644
--- a/src/backend/postmaster/datachecksum_state.c
+++ b/src/backend/postmaster/datachecksum_state.c
@@ -391,6 +391,7 @@ static void FreeDatabaseList(List *dblist);
static DataChecksumsWorkerResult ProcessDatabase(DataChecksumsWorkerDatabase *db);
static bool ProcessAllDatabases(void);
static bool ProcessSingleRelationFork(Relation reln, ForkNumber forkNum, BufferAccessStrategy strategy);
+static void ResetDataChecksumsProgressCounters(void);
static void launcher_cancel_handler(SIGNAL_ARGS);
static void WaitForAllTransactionsToFinish(void);
@@ -698,7 +699,19 @@ ProcessSingleRelationFork(Relation reln, ForkNumber forkNum, BufferAccessStrateg
snprintf(activity, sizeof(activity) - 1, "processing: %s.%s (%s, %u blocks)",
(relns ? relns : ""), RelationGetRelationName(reln), forkNames[forkNum], numblocks);
pgstat_report_activity(STATE_RUNNING, activity);
- pgstat_progress_update_param(PROGRESS_DATACHECKSUMS_BLOCKS_TOTAL, numblocks);
+ {
+ const int index[] = {
+ PROGRESS_DATACHECKSUMS_BLOCKS_TOTAL,
+ PROGRESS_DATACHECKSUMS_BLOCKS_DONE
+ };
+
+ int64 vals[2];
+
+ vals[0] = numblocks;
+ vals[1] = 0;
+
+ pgstat_progress_update_multi_param(2, index, vals);
+ }
if (relns)
pfree(relns);
@@ -764,6 +777,29 @@ ProcessSingleRelationFork(Relation reln, ForkNumber forkNum, BufferAccessStrateg
return true;
}
+/*
+ * Initialize all data checksum progress counters to be displayed as NULL.
+ */
+static void
+ResetDataChecksumsProgressCounters(void)
+{
+ const int index[] = {
+ PROGRESS_DATACHECKSUMS_DBS_TOTAL,
+ PROGRESS_DATACHECKSUMS_DBS_DONE,
+ PROGRESS_DATACHECKSUMS_RELS_TOTAL,
+ PROGRESS_DATACHECKSUMS_RELS_DONE,
+ PROGRESS_DATACHECKSUMS_BLOCKS_TOTAL,
+ PROGRESS_DATACHECKSUMS_BLOCKS_DONE,
+ };
+
+ int64 vals[lengthof(index)];
+
+ for (int i = 0; i < lengthof(index); i++)
+ vals[i] = -1;
+
+ pgstat_progress_update_multi_param(lengthof(index), index, vals);
+}
+
/*
* ProcessSingleRelationByOid
* Process a single relation based on oid.
@@ -1142,6 +1178,7 @@ again:
pgstat_progress_start_command(PROGRESS_COMMAND_DATACHECKSUMS,
InvalidOid);
+ ResetDataChecksumsProgressCounters();
if (operation == ENABLE_DATACHECKSUMS)
{
@@ -1269,23 +1306,14 @@ ProcessAllDatabases(void)
const int index[] = {
PROGRESS_DATACHECKSUMS_DBS_TOTAL,
PROGRESS_DATACHECKSUMS_DBS_DONE,
- PROGRESS_DATACHECKSUMS_RELS_TOTAL,
- PROGRESS_DATACHECKSUMS_RELS_DONE,
- PROGRESS_DATACHECKSUMS_BLOCKS_TOTAL,
- PROGRESS_DATACHECKSUMS_BLOCKS_DONE,
};
- int64 vals[6];
+ int64 vals[2];
vals[0] = list_length(DatabaseList);
vals[1] = 0;
- /* translated to NULL */
- vals[2] = -1;
- vals[3] = -1;
- vals[4] = -1;
- vals[5] = -1;
- pgstat_progress_update_multi_param(6, index, vals);
+ pgstat_progress_update_multi_param(2, index, vals);
}
foreach_ptr(DataChecksumsWorkerDatabase, db, DatabaseList)
@@ -1581,6 +1609,7 @@ DataChecksumsWorkerMain(Datum arg)
/* worker will have a separate entry in pg_stat_progress_data_checksums */
pgstat_progress_start_command(PROGRESS_COMMAND_DATACHECKSUMS,
InvalidOid);
+ ResetDataChecksumsProgressCounters();
/*
* Get a list of all temp tables present as we start in this database. We
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 39905c2de14..6a3341356da 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2123,7 +2123,10 @@ pg_stat_progress_data_checksums| SELECT s.pid,
WHEN '-1'::integer THEN NULL::bigint
ELSE s.param2
END AS databases_total,
- s.param3 AS databases_done,
+ CASE s.param3
+ WHEN '-1'::integer THEN NULL::bigint
+ ELSE s.param3
+ END AS databases_done,
CASE s.param4
WHEN '-1'::integer THEN NULL::bigint
ELSE s.param4
--
2.55.0
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Subject: Re: Fix pg_stat_progress_data_checksums counter initialization
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