FAQ about precheck - Data Transmission Service - Alibaba Cloud Documentation Center

This topic provides answers to frequently asked questions about PolarDB for Orac during the precheck process.

Why does the account of my destination database have insufficient permissions to migrate data?

Problem description
The account of the destination database does not have sufficient permissions.

Cause
You set the Username parameter to a standard account for the destination database when you created a migration project.
Solution
Create another migration project. Set the Username parameter to a privileged account for the destination database. Then, set the Password parameter to a password for the privileged account.
Note
You can create a privileged account in the console of the destination database instance. For more information, see Create database accounts.

Why is the plug-in of a destination database missing?

Problem description
The plug-in failed to be verified. The plug-in is missing in the destination database.

Cause
The plug-in on which the migration objects depend is not installed on the destination database server. If your software database uses an earlier kernel version, the automatic check performed by the database may return inaccurate results. In this case, the precheck result prevails.
Solution
1. Use a privileged account to log on to the destination database. The account is specified when the migration project is created.
2. Execute the following SQL statement to install the missing plug-in: Replace the value of Plug-in name with the name of the missing plug-in that is prompted. Replace the value of Schema-in name with the actual schema name.
```
CREATE EXTENSION IF NOT EXISTS "Plug-in name" schema "Schema-in name";
```
  If multiple plug-ins are missing, execute the preceding statement multiple times. The missing plug-ins [polar_anydata,polar_nvl,polar_agg] are used in the following example:
```
CREATE EXTENSION IF NOT EXISTS "polar_anydata" schema "pg_catalog";
CREATE EXTENSION IF NOT EXISTS "polar_nvl" schema "pg_catalog";
CREATE EXTENSION IF NOT EXISTS "polar_agg" schema "pg_catalog";
```
  Note
  If a returned message indicates that the destination database does not support the plug-in, upgrade the database, and then execute the SQL statement again. For more information about how to upgrade the database, see Upgrade the major engine version. After you upgrade the database and install the missing plug-in, perform the following steps:
  1. Create a project to evaluate the destination database.
  2. Create a migration project and select the project created in Step i.

Why is the specified database version in a database evaluation project inconsistent with the actual database version?

Cause
- If you use the latest destination database version and Advanced Database & Application Migration (ADAM) cannot evaluate this version, ignore this issue.
- If the destination database version is earlier than the evaluation version, go to the console of the destination database to upgrade the version. Then, perform the precheck again.
  Note
  This is not an urgent issue that may cause data migration failure. You can ignore this issue if you have a tight schedule.
Solution
1. Create a project to evaluate the destination database.
2. Create a migration project and select the project created in Step a.

Why is the character encoding of the destination database different from that of the source database?

Cause
In the precheck prompt message, the character encoding of the destination database is provided. The message prompts you to check whether the character encoding of the destination database is the same as that of the source database.

Solution
- If the character encoding of the destination database is the same as that of the source database, ignore this issue.
- If the character encoding of the destination database is different from that of the source database, change the character encoding of the destination database to the character encoding of the source database in the console of the destination database.

Why is the system time of the source database different from that of the destination database?

Cause
In the precheck prompt message, the current system time of the destination database is provided. The message prompts you to check whether the system time of the source database is the same as that of the destination database.

Solution
- If the system time of the source database is the same as that of the destination database, ignore this issue.
- If the system time of the source database is different from that of the destination database, modify the system time of the source database or the destination database based on your business requirements.

Why are the resources of the destination database insufficient?

Cause
The disk capacity of the destination database is insufficient.

Solution
Increase the storage capacity of the destination database.