Postgres 18 changes 3/n: new fields in Checkpointer

mdevan · mdevan · commit 78926c621fcb · 2025-09-25T10:36:43.000+05:30
diff --git a/collector/collect.go b/collector/collect.go
@@ -3061,13 +3061,19 @@ func (c *collector) getCheckpointer() {
 
 	q := `SELECT num_timed, num_requested, restartpoints_timed,
 				restartpoints_req, restartpoints_done, write_time, sync_time,
-				buffers_written, COALESCE(EXTRACT(EPOCH FROM stats_reset)::bigint, 0)
+				buffers_written, COALESCE(EXTRACT(EPOCH FROM stats_reset)::bigint, 0),
+				num_done, slru_written
 		    FROM pg_stat_checkpointer`
+	if c.version < pgv18 { // num_done and slru_written only in pg >= v18
+		q = strings.Replace(q, "num_done", "0", 1)
+		q = strings.Replace(q, "slru_written", "0", 1)
+	}
 
 	var ckp pgmetrics.Checkpointer
 	err := c.db.QueryRowContext(ctx, q).Scan(&ckp.NumTimed, &ckp.NumRequested,
 		&ckp.RestartpointsTimed, &ckp.RestartpointsRequested, &ckp.RestartpointsDone,
-		&ckp.WriteTime, &ckp.SyncTime, &ckp.BuffersWritten, &ckp.StatsReset)
+		&ckp.WriteTime, &ckp.SyncTime, &ckp.BuffersWritten, &ckp.StatsReset,
+		&ckp.NumDone, &ckp.SLRUWritten)
 	if err != nil {
 		log.Fatalf("pg_stat_checkpointer query failed: %v", err)
 	}
diff --git a/model.go b/model.go
@@ -1145,4 +1145,7 @@ type Checkpointer struct {
 	SyncTime               float64 `json:"sync_time"`
 	BuffersWritten         int64   `json:"buffers_written"`
 	StatsReset             int64   `json:"stats_reset"`
+	// following fields present only in schema 1.19 and later
+	NumDone     int64 `json:"num_done,omitempty"`     // pg >= v18
+	SLRUWritten int64 `json:"slru_written,omitempty"` // pg >= v18
 }

Original file line number	Diff line number	Diff line change
`@@ -1145,4 +1145,7 @@ type Checkpointer struct {`
`1145`	`1145`	SyncTime float64 `json:"sync_time"`
`1146`	`1146`	BuffersWritten int64 `json:"buffers_written"`
`1147`	`1147`	StatsReset int64 `json:"stats_reset"`
	`1148`	`+ // following fields present only in schema 1.19 and later`
	`1149`	+ NumDone int64 `json:"num_done,omitempty"` // pg >= v18
	`1150`	+ SLRUWritten int64 `json:"slru_written,omitempty"` // pg >= v18
`1148`	`1151`	`}`