Fix inconsistent reporting of checkpointer stats.

Previously, the pg_stat_checkpointer view and the checkpoint completion
log message could show different numbers for buffers written
during checkpoints. The view only counted shared buffers,
while the log message included both shared and SLRU buffers,
causing inconsistencies.

This commit resolves the issue by updating both the view and the log message
to separately report shared and SLRU buffers written during checkpoints.
A new slru_written column is added to the pg_stat_checkpointer view
to track SLRU buffers, while the existing buffers_written column now
tracks only shared buffers. This change would help users distinguish
between the two types of buffers, in the pg_stat_checkpointer view and
the checkpoint complete log message, respectively.

Bump catalog version.

Author: Nitin Jadhav
Reviewed-by: Bharath Rupireddy, Michael Paquier, Kyotaro Horiguchi, Robert Haas
Reviewed-by: Andres Freund, vignesh C, Fujii Masao
Discussion: https://postgr.es/m/CAMm1aWb18EpT0whJrjG+-nyhNouXET6ZUw0pNYYAe+NezpvsAA@mail.gmail.com

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 48ffe87241c844941e3541daa449c993952ae964..331315f8d3c17660d47340bc4b09e89a0fb60ede 100644 (file)
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -3127,7 +3127,16 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        <structfield>buffers_written</structfield> <type>bigint</type>
       </para>
       <para>
-       Number of buffers written during checkpoints and restartpoints
+       Number of shared buffers written during checkpoints and restartpoints
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>slru_written</structfield> <type>bigint</type>
+      </para>
+      <para>
+        Number of SLRU buffers written during checkpoints and restartpoints
       </para></entry>
      </row>
 

diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index e7f73bf4275a14cb4afb5a21120364b7acc9f666..889eff1815b48887577a857a2a6da5586e408f27 100644 (file)
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -716,9 +716,12 @@ SlruInternalWritePage(SlruCtl ctl, int slotno, SlruWriteAll fdata)
    if (!ok)
        SlruReportIOError(ctl, pageno, InvalidTransactionId);
 
-   /* If part of a checkpoint, count this as a buffer written. */
+   /* If part of a checkpoint, count this as a SLRU buffer written. */
    if (fdata)
-       CheckpointStats.ckpt_bufs_written++;
+   {
+       CheckpointStats.ckpt_slru_written++;
+       PendingCheckpointerStats.slru_written++;
+   }
 }
 
 /*

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 64304d77d3778c34876796090de2af24f6cbf915..9102c8d772e7129152ad1a541cf5962474e74c03 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6727,14 +6727,15 @@ LogCheckpointEnd(bool restartpoint)
     */
    if (restartpoint)
        ereport(LOG,
-               (errmsg("restartpoint complete: wrote %d buffers (%.1f%%); "
-                       "%d WAL file(s) added, %d removed, %d recycled; "
-                       "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; "
-                       "sync files=%d, longest=%ld.%03d s, average=%ld.%03d s; "
-                       "distance=%d kB, estimate=%d kB; "
-                       "lsn=%X/%X, redo lsn=%X/%X",
+               (errmsg("restartpoint complete: wrote %d buffers (%.1f%%), "
+                       "wrote %d SLRU buffers; %d WAL file(s) added, "
+                       "%d removed, %d recycled; write=%ld.%03d s, "
+                       "sync=%ld.%03d s, total=%ld.%03d s; sync files=%d, "
+                       "longest=%ld.%03d s, average=%ld.%03d s; distance=%d kB, "
+                       "estimate=%d kB; lsn=%X/%X, redo lsn=%X/%X",
                        CheckpointStats.ckpt_bufs_written,
                        (double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
+                       CheckpointStats.ckpt_slru_written,
                        CheckpointStats.ckpt_segs_added,
                        CheckpointStats.ckpt_segs_removed,
                        CheckpointStats.ckpt_segs_recycled,
@@ -6750,14 +6751,15 @@ LogCheckpointEnd(bool restartpoint)
                        LSN_FORMAT_ARGS(ControlFile->checkPointCopy.redo))));
    else
        ereport(LOG,
-               (errmsg("checkpoint complete: wrote %d buffers (%.1f%%); "
-                       "%d WAL file(s) added, %d removed, %d recycled; "
-                       "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; "
-                       "sync files=%d, longest=%ld.%03d s, average=%ld.%03d s; "
-                       "distance=%d kB, estimate=%d kB; "
-                       "lsn=%X/%X, redo lsn=%X/%X",
+               (errmsg("checkpoint complete: wrote %d buffers (%.1f%%), "
+                       "wrote %d SLRU buffers; %d WAL file(s) added, "
+                       "%d removed, %d recycled; write=%ld.%03d s, "
+                       "sync=%ld.%03d s, total=%ld.%03d s; sync files=%d, "
+                       "longest=%ld.%03d s, average=%ld.%03d s; distance=%d kB, "
+                       "estimate=%d kB; lsn=%X/%X, redo lsn=%X/%X",
                        CheckpointStats.ckpt_bufs_written,
                        (double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
+                       CheckpointStats.ckpt_slru_written,
                        CheckpointStats.ckpt_segs_added,
                        CheckpointStats.ckpt_segs_removed,
                        CheckpointStats.ckpt_segs_recycled,

diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 49109dbdc86f8e47ae13a09317377b0c1e9ae649..3456b821bc537c6833341538ab4bcce0ffb8a9c5 100644 (file)
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1145,6 +1145,7 @@ CREATE VIEW pg_stat_checkpointer AS
         pg_stat_get_checkpointer_write_time() AS write_time,
         pg_stat_get_checkpointer_sync_time() AS sync_time,
         pg_stat_get_checkpointer_buffers_written() AS buffers_written,
+        pg_stat_get_checkpointer_slru_written() AS slru_written,
         pg_stat_get_checkpointer_stat_reset_time() AS stats_reset;
 
 CREATE VIEW pg_stat_io AS

diff --git a/src/backend/utils/activity/pgstat_checkpointer.c b/src/backend/utils/activity/pgstat_checkpointer.c
index 4a0a2d1493a4fc4c989901cdfa3c675744827acb..5a3fb4a9e09add7459049fa198aaea35b22ce024 100644 (file)
--- a/src/backend/utils/activity/pgstat_checkpointer.c
+++ b/src/backend/utils/activity/pgstat_checkpointer.c
@@ -56,6 +56,7 @@ pgstat_report_checkpointer(void)
    CHECKPOINTER_ACC(write_time);
    CHECKPOINTER_ACC(sync_time);
    CHECKPOINTER_ACC(buffers_written);
+   CHECKPOINTER_ACC(slru_written);
 #undef CHECKPOINTER_ACC
 
    pgstat_end_changecount_write(&stats_shmem->changecount);
@@ -135,5 +136,6 @@ pgstat_checkpointer_snapshot_cb(void)
    CHECKPOINTER_COMP(write_time);
    CHECKPOINTER_COMP(sync_time);
    CHECKPOINTER_COMP(buffers_written);
+   CHECKPOINTER_COMP(slru_written);
 #undef CHECKPOINTER_COMP
 }

diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 17b0fc02ef01ba4e7f6b1bff390ef976fbd44d88..f7b50e0b5af6a20a8d80ebb3d8b0417069459ac8 100644 (file)
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1221,6 +1221,12 @@ pg_stat_get_checkpointer_buffers_written(PG_FUNCTION_ARGS)
    PG_RETURN_INT64(pgstat_fetch_stat_checkpointer()->buffers_written);
 }
 
+Datum
+pg_stat_get_checkpointer_slru_written(PG_FUNCTION_ARGS)
+{
+   PG_RETURN_INT64(pgstat_fetch_stat_checkpointer()->slru_written);
+}
+
 Datum
 pg_stat_get_bgwriter_buf_written_clean(PG_FUNCTION_ARGS)
 {

diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 36f6e4e4b4e225d2b2fb31b740de068db704579e..34ad46c067bce5e4e0424bce0b28add1183fb8b0 100644 (file)
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -167,6 +167,7 @@ typedef struct CheckpointStatsData
    TimestampTz ckpt_end_t;     /* end of checkpoint */
 
    int         ckpt_bufs_written;  /* # of buffers written */
+   int         ckpt_slru_written;  /* # of SLRU buffers written */
 
    int         ckpt_segs_added;    /* # of new xlog segments created */
    int         ckpt_segs_removed;  /* # of xlog segments deleted */

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 3c89b70f9e43b2daa31e3973f70bfe052720ea51..504bbe5327677a673ecdabfcb8f162b2bb9ddedf 100644 (file)
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -57,6 +57,6 @@
  */
 
 /*                         yyyymmddN */
-#define CATALOG_VERSION_NO 202409302
+#define CATALOG_VERSION_NO 202410021
 
 #endif

diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 05fcbf75156019dd6ad36ff4934b7639b2a33f78..77f54a79e6ad92cb4c21dcb3fee161a025651c75 100644 (file)
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5847,6 +5847,11 @@
   proname => 'pg_stat_get_checkpointer_buffers_written', provolatile => 's',
   proparallel => 'r', prorettype => 'int8', proargtypes => '',
   prosrc => 'pg_stat_get_checkpointer_buffers_written' },
+{ oid => '8573',
+  descr => 'statistics: number of SLRU buffers written during checkpoints and restartpoints',
+  proname => 'pg_stat_get_checkpointer_slru_written', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => '',
+  prosrc => 'pg_stat_get_checkpointer_slru_written' },
 { oid => '6314', descr => 'statistics: last reset for the checkpointer',
   proname => 'pg_stat_get_checkpointer_stat_reset_time', provolatile => 's',
   proparallel => 'r', prorettype => 'timestamptz', proargtypes => '',

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 476acd680c01f4ff368048b199d61a0fb3563909..df53fa2d4f94250be89c37adff90949f331bc622 100644 (file)
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -301,6 +301,7 @@ typedef struct PgStat_CheckpointerStats
    PgStat_Counter write_time;  /* times in milliseconds */
    PgStat_Counter sync_time;
    PgStat_Counter buffers_written;
+   PgStat_Counter slru_written;
    TimestampTz stat_reset_timestamp;
 } PgStat_CheckpointerStats;
 

diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index f5434d8365c007e66099c565d3c74b40297533c2..2b47013f113e373e928d76197ba6cadcde79870e 100644 (file)
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1831,6 +1831,7 @@ pg_stat_checkpointer| SELECT pg_stat_get_checkpointer_num_timed() AS num_timed,
     pg_stat_get_checkpointer_write_time() AS write_time,
     pg_stat_get_checkpointer_sync_time() AS sync_time,
     pg_stat_get_checkpointer_buffers_written() AS buffers_written,
+    pg_stat_get_checkpointer_slru_written() AS slru_written,
     pg_stat_get_checkpointer_stat_reset_time() AS stats_reset;
 pg_stat_database| SELECT oid AS datid,
     datname,