MyCATApache/Mycat-Server · error · ConfigException

newSchema: is not exists!

Error message

newSchema:{schemaName} is not exists!

What it means

loadMigratorTables also validates the schema name against the NEW schema configuration (schema.xml after migration). If the schema exists in the old config but not in the new one, a ConfigException is thrown. Migration requires the schema to exist in both configurations so tables can be compared and moved.

Solutions

  1. Add the missing schema definition to the new schema.xml (with its tables and data nodes).
  2. Or update tablesFile.properties to use the schema's new name as defined in the new schema.xml.
  3. Confirm both schema.xml versions define the same schema names before rerunning the migrator.

Example fix

// before: new schema.xml lacks the schema
<schema name="ordersdb" ...> <!-- missing -->
// after
<schema name="ordersdb" checkSQLschema="false" dataNode="dn1"> ... </schema>
Defensive patterns

Strategy: validation

Validate before calling

Set<String> newSchemaNames = newSchemas.keySet().stream()
    .map(String::toLowerCase).collect(Collectors.toSet());
for (String schema : prop.stringPropertyNames()) {
    if (!newSchemaNames.contains(schema.toLowerCase().trim())) {
        throw new IllegalArgumentException("schema missing from NEW config: " + schema);
    }
}

Try / catch

try {
    comparer.compare();
} catch (ConfigException e) {
    if (e.getMessage().startsWith("newSchema:")) {
        // add the schema to new schema.xml or rename the entry in tablesFile.properties
    }
    throw e;
}

Prevention

When it happens

Trigger: tablesFile.properties lists a schema present in the old schema.xml but missing from the new schema.xml — typically the schema was dropped or renamed in the target configuration.

Common situations: Operator removed the schema from the new schema.xml while planning data redistribution; renamed schema during migration but forgot to update tablesFile.properties; typo when writing the new schema.xml.

Understand the failure class

Background: "Not found" and "does not exist" errors: why "Task not found", "No such folder", and "Can't find" fire when a lookup comes back empty — this error's family across 14 libraries.

Related errors

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/cab0c92be6ef4e8a. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/util/dataMigrator/ConfigComparer.java:136

	}
	
	private String[] getTables(String tables){
		if(tables.equalsIgnoreCase("all") || tables.isEmpty()){
			return new String[]{};
		}else{
			return tables.split(",");
		}
	}
	
	/*
	 * 加载迁移表信息，tables大小为0表示迁移schema下所有表
	 */
	private void loadMigratorTables(String schemaName,String[] tables){
		if(!DataMigratorUtil.isKeyExistIgnoreCase(oldSchemas, schemaName)){
			throw new ConfigException("oldSchema:"+schemaName+" is not exists!");
		}
		if(!DataMigratorUtil.isKeyExistIgnoreCase(newSchemas,schemaName)){
			throw new ConfigException("newSchema:"+schemaName+" is not exists!");
		}
		Map<String, TableConfig> oldTables =  DataMigratorUtil.getValueIgnoreCase(oldSchemas, schemaName).getTables();
		Map<String, TableConfig> newTables = DataMigratorUtil.getValueIgnoreCase(newSchemas, schemaName).getTables();
		if(tables.length>0){
			//指定schema下的表进行迁移
			for(int i =0;i<tables.length;i++){
				TableConfig oldTable =  DataMigratorUtil.getValueIgnoreCase(oldTables,tables[i]);
				TableConfig newTable = DataMigratorUtil.getValueIgnoreCase(newTables,tables[i]);
				loadMigratorTable(oldTable, newTable,schemaName,tables[i]);
			}
		}else{
			//迁移schema下所有的表
			//校验新旧schema中的table配置是否一致
			Set<String> oldSet = oldTables.keySet();
			Set<String> newSet = newTables.keySet();
			if(!oldSet.equals(newSet)){
				throw new ConfigException("new & old table config is not equal!");
			}

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