Improvements to the transaction list (#12085)

Author: Alek5andr-Kotov

ydb/core/persqueue/pq_impl_app.cpp

@@ -123,7 +123,7 @@ class TMonitoringProxy : public TActorBootstrapped<TMonitoringProxy> {
                                                     str << tx.TxId;
                                                 }
                                             }
-                                            TABLED() {str << tx.Step;}
+                                            TABLED() {str << GetTxStep(tx);}
                                             TABLED() {str << NKikimrPQ::TTransaction_EState_Name(tx.State);}
                                             TABLED() {str << tx.MinStep;}
                                             TABLED() {str << tx.MaxStep;}
@@ -147,6 +147,13 @@ class TMonitoringProxy : public TActorBootstrapped<TMonitoringProxy> {
         Die(ctx);
     }
 
+    static TString GetTxStep(const TTransactionSnapshot& tx) {
+        if (tx.Step == Max<ui64>()) {
+            return "-";
+        }
+        return ToString(tx.Step);
+    }
+
     void Wakeup(const TActorContext& ctx) {
         Reply(ctx);
     }