enhance deletiontime detection

db/helpers.go

@@ -504,6 +504,67 @@ GROUP BY
 	return insert, nil
 }
 
+// RefineCreationDeletionFromUnion walks all snapshot rows in a period and tightens CreationTime/DeletionTime
+// by using the first and last observed samples and the first sample after disappearance.
+func RefineCreationDeletionFromUnion(ctx context.Context, dbConn *sqlx.DB, summaryTable, unionQuery string) error {
+	if unionQuery == "" {
+		return fmt.Errorf("union query is empty")
+	}
+	if _, err := SafeTableName(summaryTable); err != nil {
+		return err
+	}
+	sql := fmt.Sprintf(`
+WITH snapshots AS (
+%s
+), timeline AS (
+  SELECT
+    s."VmId",
+    s."VmUuid",
+    s."Name",
+    s."Vcenter",
+    MIN(NULLIF(s."CreationTime", 0)) AS any_creation,
+    MIN(s."SnapshotTime") AS first_seen,
+    MAX(s."SnapshotTime") AS last_seen
+  FROM snapshots s
+  GROUP BY s."VmId", s."VmUuid", s."Name", s."Vcenter"
+)
+UPDATE %s dst
+SET
+  "CreationTime" = CASE
+    WHEN t.any_creation IS NOT NULL AND t.any_creation > 0 THEN LEAST(COALESCE(NULLIF(dst."CreationTime", 0), t.any_creation), t.any_creation)
+    WHEN t.first_seen IS NOT NULL THEN LEAST(COALESCE(NULLIF(dst."CreationTime", 0), t.first_seen), t.first_seen)
+    ELSE dst."CreationTime"
+  END,
+  "DeletionTime" = CASE
+    WHEN t_last_after IS NOT NULL
+         AND (dst."DeletionTime" IS NULL OR dst."DeletionTime" = 0 OR t_last_after < dst."DeletionTime")
+      THEN t_last_after
+    ELSE dst."DeletionTime"
+  END
+FROM (
+  SELECT
+    tl.*,
+    (
+      SELECT MIN(s2."SnapshotTime")
+      FROM snapshots s2
+      WHERE s2."Vcenter" = tl."Vcenter"
+        AND COALESCE(s2."VmId", '') = COALESCE(tl."VmId", '')
+        AND s2."SnapshotTime" > tl.last_seen
+    ) AS t_last_after
+  FROM timeline tl
+) t
+WHERE dst."Vcenter" = t."Vcenter"
+  AND (
+    (dst."VmId" IS NOT DISTINCT FROM t."VmId")
+    OR (dst."VmUuid" IS NOT DISTINCT FROM t."VmUuid")
+    OR (dst."Name" IS NOT DISTINCT FROM t."Name")
+  );
+`, unionQuery, summaryTable)
+
+	_, err := dbConn.ExecContext(ctx, sql)
+	return err
+}
+
 // BuildMonthlySummaryInsert returns the SQL to aggregate daily summaries into a monthly summary table.
 func BuildMonthlySummaryInsert(tableName string, unionQuery string) (string, error) {
 	if _, err := SafeTableName(tableName); err != nil {

internal/tasks/dailyAggregate.go

@@ -129,6 +129,9 @@ func (c *CronTask) aggregateDailySummary(ctx context.Context, targetTime time.Ti
 		c.Logger.Error("failed to aggregate daily inventory", "error", err, "date", dayStart.Format("2006-01-02"))
 		return err
 	}
+	if err := db.RefineCreationDeletionFromUnion(ctx, dbConn, summaryTable, unionQuery); err != nil {
+		c.Logger.Warn("failed to refine creation/deletion times", "error", err, "table", summaryTable)
+	}
 	rowCount, err := db.TableRowCount(ctx, dbConn, summaryTable)
 	if err != nil {
 		c.Logger.Warn("unable to count daily summary rows", "error", err, "table", summaryTable)