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+# Upgrade Features in V2.3.0: Instructions for Using pg_clean
+
+## 1. Install the pg_clean tool:
+Connect to any primary CN (Coordinate Node):
+
+```
+CREATE EXTENSION pg_clean;
+```
+
+## 2. Construct a test case for residual two-phase transactions:
+Session 1 - CN1
+
+```
+begin; 
+create table a (id int); 
+prepare transaction 'create_a';
+set xc_maintenance_mode = on;
+execute direct on (dn002) 'rollback prepared ''create_a''';
+set xc_maintenance_mode = off;
+\q
+```
+
+In this test case, we created a two-phase transaction with a GID (Global Identifier) of 'create_a', 
+then turned on xc_maintenance_mode, causing the transaction to only execute a rollback on dn002.
+
+## 3. Find residual two-phase transactions in the cluster:
+Session 2 - CN2
+
+```
+select * from pg_clean_check_txn();
+```
+
+![pg_clean_check_txn](images/v.2.3.0_pg_clean_check_txn.png)
+
+The above image shows residual two-phase transactions in the cluster. The GID represents the global
+identifier of the transaction, global_transaction_status indicates the global status of the transaction,
+and transaction_status_on_allnodes shows the status of the transaction on all nodes.
+
+## 4. Check 2PC residual filenames
+
+Query all residual 2PC filenames in the pg_2pc directory of the data folder on node cn1.
+
+Session 1 - CN1
+
+```
+postgres=# select * from pgxc_get_record_list();
+ pgxc_get_record_list 
+----------------------
+create_a
+(1 row)
+```
+
+## 5. Clean up residual two-phase transactions in the cluster:
+Session 2 - CN2
+
+```
+select * from pg_clean_execute();
+```
+
+![pg_clean_execute](images/v2.3.0_pg_clean_execute.png)
+
+The above image prints out all residual two-phase transactions and the operations executed on them. 
+The operation column indicates the action performed on the transaction on each node, and operation_status
+indicates whether the operation was successful. Since the global transaction status of this transaction is ABORT,
+we go to each node with a status of prepare and execute a rollback operation on the transaction.
+
+## 6. Check for residual file records of the cleaned two-phase transactions:
+Session 1 - CN1
+
+```
+postgres=# select * from pgxc_get_record_list();
+pgxc_get_record_list 
+----------------------
+```
+
+Since the pg_clean_execute in the previous step was successful, the file records of the rolled-back transaction 'create_a' 
+have been deleted from all nodes. Here we check on cn1 for all 2PC file records, which shows as empty, and the result is correct.