Track block level checksum failures in pg_stat_database

This adds a column that counts how many checksum failures have occurred
on files belonging to a specific database. Both checksum failures
during normal backend processing and those created when a base backup
detects a checksum failure are counted.

Author: Magnus Hagander
Reviewed by: Julien Rouhaud

doc/src/sgml/monitoring.sgml

@@ -2508,6 +2508,11 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
      <entry><type>bigint</type></entry>
      <entry>Number of deadlocks detected in this database</entry>
     </row>
+    <row>
+     <entry><structfield>checksum_failures</structfield></entry>
+     <entry><type>bigint</type></entry>
+     <entry>Number of data page checksum failures detected in this database</entry>
+    </row>
     <row>
      <entry><structfield>blk_read_time</structfield></entry>
      <entry><type>double precision</type></entry>

src/backend/catalog/system_views.sql

@@ -823,6 +823,7 @@ CREATE VIEW pg_stat_database AS
             pg_stat_get_db_temp_files(D.oid) AS temp_files,
             pg_stat_get_db_temp_bytes(D.oid) AS temp_bytes,
             pg_stat_get_db_deadlocks(D.oid) AS deadlocks,
+            pg_stat_get_db_checksum_failures(D.oid) AS checksum_failures,
             pg_stat_get_db_blk_read_time(D.oid) AS blk_read_time,
             pg_stat_get_db_blk_write_time(D.oid) AS blk_write_time,
             pg_stat_get_db_stat_reset_time(D.oid) AS stats_reset

src/backend/postmaster/pgstat.c

@@ -334,6 +334,7 @@ static void pgstat_recv_funcstat(PgStat_MsgFuncstat *msg, int len);
 static void pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len);
 static void pgstat_recv_recoveryconflict(PgStat_MsgRecoveryConflict *msg, int len);
 static void pgstat_recv_deadlock(PgStat_MsgDeadlock *msg, int len);
+static void pgstat_recv_checksum_failure(PgStat_MsgChecksumFailure *msg, int len);
 static void pgstat_recv_tempfile(PgStat_MsgTempFile *msg, int len);
 
 /* ------------------------------------------------------------
@@ -1518,6 +1519,40 @@ pgstat_report_deadlock(void)
 	pgstat_send(&msg, sizeof(msg));
 }
 
+
+
+/* --------
+ * pgstat_report_checksum_failures_in_db(dboid, failure_count) -
+ *
+ *	Tell the collector about one or more checksum failures.
+ * --------
+ */
+void
+pgstat_report_checksum_failures_in_db(Oid dboid, int failurecount)
+{
+	PgStat_MsgChecksumFailure msg;
+
+	if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
+		return;
+
+	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_CHECKSUMFAILURE);
+	msg.m_databaseid = dboid;
+	msg.m_failurecount = failurecount;
+	pgstat_send(&msg, sizeof(msg));
+}
+
+/* --------
+ * pgstat_report_checksum_failure() -
+ *
+ *	Tell the collector about a checksum failure.
+ * --------
+ */
+void
+pgstat_report_checksum_failure(void)
+{
+	pgstat_report_checksum_failures_in_db(MyDatabaseId, 1);
+}
+
 /* --------
  * pgstat_report_tempfile() -
  *
@@ -4455,6 +4490,10 @@ PgstatCollectorMain(int argc, char *argv[])
 					pgstat_recv_tempfile((PgStat_MsgTempFile *) &msg, len);
 					break;
 
+				case PGSTAT_MTYPE_CHECKSUMFAILURE:
+					pgstat_recv_checksum_failure((PgStat_MsgChecksumFailure *) &msg, len);
+					break;
+
 				default:
 					break;
 			}
@@ -4554,6 +4593,7 @@ reset_dbentry_counters(PgStat_StatDBEntry *dbentry)
 	dbentry->n_temp_files = 0;
 	dbentry->n_temp_bytes = 0;
 	dbentry->n_deadlocks = 0;
+	dbentry->n_checksum_failures = 0;
 	dbentry->n_block_read_time = 0;
 	dbentry->n_block_write_time = 0;
 
@@ -6196,6 +6236,22 @@ pgstat_recv_deadlock(PgStat_MsgDeadlock *msg, int len)
 	dbentry->n_deadlocks++;
 }
 
+/* ----------
+ * pgstat_recv_checksum_failure() -
+ *
+ *	Process a CHECKSUMFAILURE message.
+ * ----------
+ */
+static void
+pgstat_recv_checksum_failure(PgStat_MsgChecksumFailure *msg, int len)
+{
+	PgStat_StatDBEntry *dbentry;
+
+	dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
+
+	dbentry->n_checksum_failures += msg->m_failurecount;
+}
+
 /* ----------
  * pgstat_recv_tempfile() -
  *

src/backend/replication/basebackup.c

@@ -58,7 +58,7 @@ typedef struct
 static int64 sendDir(const char *path, int basepathlen, bool sizeonly,
 		List *tablespaces, bool sendtblspclinks);
 static bool sendFile(const char *readfilename, const char *tarfilename,
-		 struct stat *statbuf, bool missing_ok);
+		 struct stat *statbuf, bool missing_ok, Oid dboid);
 static void sendFileWithContent(const char *filename, const char *content);
 static int64 _tarWriteHeader(const char *filename, const char *linktarget,
 				struct stat *statbuf, bool sizeonly);
@@ -342,7 +342,7 @@ perform_base_backup(basebackup_options *opt)
 							(errcode_for_file_access(),
 							 errmsg("could not stat file \"%s\": %m",
 									XLOG_CONTROL_FILE)));
-				sendFile(XLOG_CONTROL_FILE, XLOG_CONTROL_FILE, &statbuf, false);
+				sendFile(XLOG_CONTROL_FILE, XLOG_CONTROL_FILE, &statbuf, false, InvalidOid);
 			}
 			else
 				sendTablespace(ti->path, false);
@@ -592,7 +592,7 @@ perform_base_backup(basebackup_options *opt)
 						(errcode_for_file_access(),
 						 errmsg("could not stat file \"%s\": %m", pathbuf)));
 
-			sendFile(pathbuf, pathbuf, &statbuf, false);
+			sendFile(pathbuf, pathbuf, &statbuf, false, InvalidOid);
 
 			/* unconditionally mark file as archived */
 			StatusFilePath(pathbuf, fname, ".done");
@@ -1302,7 +1302,7 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
 
 			if (!sizeonly)
 				sent = sendFile(pathbuf, pathbuf + basepathlen + 1, &statbuf,
-								true);
+								true, isDbDir ? pg_atoi(lastDir + 1, sizeof(Oid), 0) : InvalidOid);
 
 			if (sent || sizeonly)
 			{
@@ -1358,12 +1358,15 @@ is_checksummed_file(const char *fullpath, const char *filename)
  *
  * If 'missing_ok' is true, will not throw an error if the file is not found.
  *
+ * If dboid is anything other than InvalidOid then any checksum failures detected
+ * will get reported to the stats collector.
+ *
  * Returns true if the file was successfully sent, false if 'missing_ok',
  * and the file did not exist.
  */
 static bool
 sendFile(const char *readfilename, const char *tarfilename, struct stat *statbuf,
-		 bool missing_ok)
+		 bool missing_ok, Oid dboid)
 {
 	FILE	   *fp;
 	BlockNumber blkno = 0;
@@ -1580,6 +1583,9 @@ sendFile(const char *readfilename, const char *tarfilename, struct stat *statbuf
 		ereport(WARNING,
 				(errmsg("file \"%s\" has a total of %d checksum verification "
 						"failures", readfilename, checksum_failures)));
+
+		if (dboid != InvalidOid)
+			pgstat_report_checksum_failures_in_db(dboid, checksum_failures);
 	}
 	total_checksum_failures += checksum_failures;
 

src/backend/storage/page/bufpage.c

@@ -17,6 +17,7 @@
 #include "access/htup_details.h"
 #include "access/itup.h"
 #include "access/xlog.h"
+#include "pgstat.h"
 #include "storage/checksum.h"
 #include "utils/memdebug.h"
 #include "utils/memutils.h"
@@ -151,6 +152,8 @@ PageIsVerified(Page page, BlockNumber blkno)
 				 errmsg("page verification failed, calculated checksum %u but expected %u",
 						checksum, p->pd_checksum)));
 
+		pgstat_report_checksum_failure();
+
 		if (header_sane && ignore_checksum_failure)
 			return true;
 	}

src/backend/utils/adt/pgstatfuncs.c

@@ -1497,6 +1497,21 @@ pg_stat_get_db_deadlocks(PG_FUNCTION_ARGS)
 	PG_RETURN_INT64(result);
 }
 
+Datum
+pg_stat_get_db_checksum_failures(PG_FUNCTION_ARGS)
+{
+	Oid			dbid = PG_GETARG_OID(0);
+	int64		result;
+	PgStat_StatDBEntry *dbentry;
+
+	if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+		result = 0;
+	else
+		result = (int64) (dbentry->n_checksum_failures);
+
+	PG_RETURN_INT64(result);
+}
+
 Datum
 pg_stat_get_db_blk_read_time(PG_FUNCTION_ARGS)
 {

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201903063
+#define CATALOG_VERSION_NO	201903091
 
 #endif

src/include/catalog/pg_proc.dat

@@ -5227,6 +5227,10 @@
   proname => 'pg_stat_get_db_deadlocks', provolatile => 's', proparallel => 'r',
   prorettype => 'int8', proargtypes => 'oid',
   prosrc => 'pg_stat_get_db_deadlocks' },
+{ oid => '3426', descr => 'statistics: checksum failures detected in database',
+  proname => 'pg_stat_get_db_checksum_failures', provolatile => 's', proparallel => 'r',
+  prorettype => 'int8', proargtypes => 'oid',
+  prosrc => 'pg_stat_get_db_checksum_failures' },
 { oid => '3074', descr => 'statistics: last reset for a database',
   proname => 'pg_stat_get_db_stat_reset_time', provolatile => 's',
   proparallel => 'r', prorettype => 'timestamptz', proargtypes => 'oid',

src/include/pgstat.h

@@ -64,7 +64,8 @@ typedef enum StatMsgType
 	PGSTAT_MTYPE_FUNCPURGE,
 	PGSTAT_MTYPE_RECOVERYCONFLICT,
 	PGSTAT_MTYPE_TEMPFILE,
-	PGSTAT_MTYPE_DEADLOCK
+	PGSTAT_MTYPE_DEADLOCK,
+	PGSTAT_MTYPE_CHECKSUMFAILURE
 } StatMsgType;
 
 /* ----------
@@ -530,6 +531,18 @@ typedef struct PgStat_MsgDeadlock
 	Oid			m_databaseid;
 } PgStat_MsgDeadlock;
 
+/* ----------
+ * PgStat_MsgChecksumFailure	Sent by the backend to tell the collector
+ *								about checksum failures noticed.
+ * ----------
+ */
+typedef struct PgStat_MsgChecksumFailure
+{
+	PgStat_MsgHdr m_hdr;
+	Oid			m_databaseid;
+	int			m_failurecount;
+} PgStat_MsgChecksumFailure;
+
 
 /* ----------
  * PgStat_Msg					Union over all possible messages.
@@ -593,6 +606,7 @@ typedef struct PgStat_StatDBEntry
 	PgStat_Counter n_temp_files;
 	PgStat_Counter n_temp_bytes;
 	PgStat_Counter n_deadlocks;
+	PgStat_Counter n_checksum_failures;
 	PgStat_Counter n_block_read_time;	/* times in microseconds */
 	PgStat_Counter n_block_write_time;
 
@@ -1200,6 +1214,8 @@ extern void pgstat_report_analyze(Relation rel,
 
 extern void pgstat_report_recovery_conflict(int reason);
 extern void pgstat_report_deadlock(void);
+extern void pgstat_report_checksum_failures_in_db(Oid dboid, int failurecount);
+extern void pgstat_report_checksum_failure(void);
 
 extern void pgstat_initialize(void);
 extern void pgstat_bestart(void);

src/test/regress/expected/rules.out

@@ -1817,6 +1817,7 @@ pg_stat_database| SELECT d.oid AS datid,
     pg_stat_get_db_temp_files(d.oid) AS temp_files,
     pg_stat_get_db_temp_bytes(d.oid) AS temp_bytes,
     pg_stat_get_db_deadlocks(d.oid) AS deadlocks,
+    pg_stat_get_db_checksum_failures(d.oid) AS checksum_failures,
     pg_stat_get_db_blk_read_time(d.oid) AS blk_read_time,
     pg_stat_get_db_blk_write_time(d.oid) AS blk_write_time,
     pg_stat_get_db_stat_reset_time(d.oid) AS stats_reset