feat(query-api): add richer stats and retention

internal/store/postgres/events.go

@@ -54,4 +54,55 @@ on conflict (event_id) do nothing
 	return err
 }
 
+func (d *DB) InsertEventBatch(ctx context.Context, events []InsertEvent) error {
+	if len(events) == 0 {
+		return nil
+	}
+	if len(events) == 1 {
+		return d.InsertEvent(ctx, events[0])
+	}
+
+	tx, err := d.sql.BeginTx(ctx, nil)
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+
+	stmt, err := tx.PrepareContext(ctx, `
+INSERT INTO events (
+  event_id, ts, type, session_id, run_id, trace_id, span_id, parent_span_id,
+  source_framework, client_id, payload
+) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11)
+ON CONFLICT (event_id) DO NOTHING
+`)
+	if err != nil {
+		return err
+	}
+	defer stmt.Close()
+
+	for _, e := range events {
+		payload, err := json.Marshal(e.Payload)
+		if err != nil {
+			return err
+		}
+		_, err = stmt.ExecContext(ctx, e.EventID, e.TS, e.Type, e.SessionID, e.RunID,
+			e.TraceID, e.SpanID, e.ParentSpanID, e.SourceFramework, e.ClientID, payload)
+		if err != nil {
+			return err
+		}
+	}
+
+	return tx.Commit()
+}
+
+// DeleteOlderThan removes events with ts older than the given cutoff.
+// Returns the number of rows deleted.
+func (d *DB) DeleteOlderThan(ctx context.Context, cutoff time.Time) (int64, error) {
+	result, err := d.sql.ExecContext(ctx, `DELETE FROM events WHERE ts < $1`, cutoff)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
 var ErrMissingField = errors.New("missing required field")