Checking Ledger Data Consistency

Prerequisites

The database is running properly, and a series of addition, deletion, and modification operations are performed on the tamper-proof database to ensure that operation records are generated in the ledger for query.

Background

Currently, the ledger database provides two verification interfaces: ledger_hist_check(text,… and ledger_gchain_check(text…. When a common user invokes a verification interface, only the tables that the user has the permission to access can be verified.
The interface for verifying the tamper-proof user table and user history table is pg_catalog.ledger_hist_check. To verify a table, run the following command:
```
SELECT pg_catalog.ledger_hist_check(schema_name text,table_name text);
```
If the verification is successful, the function returns t. Otherwise, the function returns f.
The pg_catalog.ledger_gchain_check interface is used to check whether the tamper-proof user table, user history table, and global blockchain table are consistent. To verify consistency, run the following command:
```
SELECT pg_catalog.ledger_gchain_check(schema_name text, table_name text);
```
If the verification is successful, the function returns t. Otherwise, the function returns f.

Procedure

Check whether the tamper-proof user table ledgernsp.usertable is consistent with the corresponding user history table.
```
openGauss=# SELECT pg_catalog.ledger_hist_check('ledgernsp', 'usertable');
```
The query result is as follows:
```
 ledger_hist_check
-------------------
 t
(1 row)
```
The query result shows that the results recorded in the tamper-proof user table and user history table are consistent.
Check whether the records in the tamper-proof ledgernsp.usertable table are the same as those in the corresponding user history table and global blockchain table.
```
openGauss=#  SELECT pg_catalog.ledger_gchain_check('ledgernsp', 'usertable');
```
The query result is as follows:
```
 ledger_gchain_check
---------------------
 t
(1 row)
```
The query result shows that the records of ledgernsp.usertable in the preceding three tables are consistent and no tampering occurs.