MyCATApache/Mycat-Server · error · ConfigException

oldSchema: is not exists!

Error message

oldSchema:{schemaName} is not exists!

What it means

loadMigratorTables validates that every schema listed in tablesFile.properties exists in the OLD schema configuration (schema.xml before migration). If the schema name is absent (case-insensitive check), migration cannot proceed and a ConfigException is thrown. This guards against migrating tables from a schema that never existed in the source cluster.

Solutions

  1. Open tablesFile.properties and check the offending key; correct the schema name to exactly match a schema in the old schema.xml.
  2. Compare against the schemas loaded from the old config and remove entries for schemas that no longer exist.
  3. Trim whitespace around the key in the properties file.
  4. Regenerate tablesFile.properties from the actual old configuration instead of hand-editing.

Example fix

// before: tablesFile.properties
ORDERS_DB:table1,table2
// after (schema exists in old schema.xml as ordersdb)
ordersdb:table1,table2
Defensive patterns

Strategy: validation

Validate before calling

Set<String> oldSchemaNames = oldSchemas.keySet().stream()
    .map(String::toLowerCase).collect(Collectors.toSet());
for (String schema : prop.stringPropertyNames()) {
    if (!oldSchemaNames.contains(schema.toLowerCase().trim())) {
        throw new IllegalArgumentException("schema not in old config: " + schema);
    }
}

Try / catch

try {
    comparer.compare();
} catch (ConfigException e) {
    if (e.getMessage().startsWith("oldSchema:")) {
        // fix tablesFile.properties schema key against old schema.xml
    }
    throw e;
}

Prevention

When it happens

Trigger: tablesFile.properties contains a key (schema name) that does not match any schema defined in the old schema.xml — due to typos, renamed schemas, case mismatches beyond the ignore-case handling, or a stale properties file.

Common situations: Operator edits tablesFile.properties and misspells a schema; schema was renamed/dropped in the old config; copy-pasting schema names with extra whitespace.

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/4130d24539293d5a. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/util/dataMigrator/ConfigComparer.java:133

			String tables = entry.getValue().toString();
			loadMigratorTables(schemaName,getTables(tables));
		}
	}
	
	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();

View on GitHub (pinned to 65f8d8beb7)