Checking Details
1. Check the following parameter values of the source and target databases. If the parameter values of the source and target databases are inconsistent, a check warning will be triggered. The warning will not block the migration task, but it may have a certain impact on your business. You can evaluate and decide whether to modify the parameters.
TimeZone, lc_monetary, lc_numeric, array_nulls, server_encoding, DateStyle, extra_float_digits, gin_fuzzy_search_limit, xmlbinary, and constraint_exclusion.
If the parameters are inconsistent, the specific impacts are as follows.
TimeZone: sets the time zone for an instance. Inconsistent values for this parameter may result in data errors after migration.
lc_monetary: sets the monetary mode for an instance. Inconsistent values for this parameter may result in errors in monetary numbers after migration.
lc_numeric: sets the numeric mode for an instance. Inconsistent values for this parameter may result in data errors after migration.
array_nulls: sets whether arrays can contain empty values. Inconsistent values for this parameter may result in data inconsistencies after migration and failure in migrating certain data.
server_encoding: sets the character set for an instance. Inconsistent values for this parameter may cause garbled characters when data is stored.
DateStyle: sets the date display format. Inconsistent values for this parameter may result in data migration failures.
extra_float_digits: sets the output precision for float values. Inconsistent values for this parameter may affect data precision. In database scenarios that require high precision, it will cause data inconsistency after migration.
gin_fuzzy_search_limit: sets the soft upper limit of the result set size returned by the GIN index. Inconsistent values for this parameter may cause the display of inconsistent data results after migration.
xmlbinary: sets the encoding method (base64 or hex) for the conversion between XML and binary data. Inconsistent values for this parameter may cause inconsistent behavior of the corresponding functions when executed in the target database compared with the source database.
constraint_exclusion: sets whether constraints are effective. Inconsistent values for this parameter may cause data inconsistency after migration.
2. Check whether the character set settings of the source and target databases are inconsistent. If inconsistent, the check task will report an error; you can change them to be consistent.
Fixing Methods
1. Use a superuser account to log in to the source database.
2. Execute the following example statements to modify the corresponding parameters:
Users can first modify parameters for the source database. If the corresponding parameters of the source database cannot be modified, you need to modify the corresponding parameters of the target database. To modify the target database, request processing via Online Support. The server_encoding parameter cannot be modified in the source database. If this parameter is abnormal, check whether it is created in the target database. If it is created and is inconsistent with the source database, you need to apply for a new instance. If it is not created, modify it by referring to the following method. Current cloud database instances only support UTF-8 and LATIN character sets.
alter system set timezone='parameter value';
alter system set lc_monetary='parameter value';
alter system set lc_numeric='parameter value';