MyCATApache/Mycat-Server · error · SQLSyntaxErrorException

not found schema :

Error message

not found schema :

What it means

While analysing a SHOW statement (analyseShowSQL, e.g. SHOW FULL COLUMNS from an information_schema query), Mycat extracts the related schema name from the SQL fields and looks it up in the server's schema config; if that schema is not defined in Mycat's configuration, it throws 'not found schema : <name>'.

Solutions

  1. Add the missing schema to schema.xml (with at least one table/datanode) and restart/reload Mycat config.
  2. Connect the client to a schema name that is defined in Mycat's configuration.
  3. Fix case/typo mismatches between the SQL's schema reference and the configured schema name.
  4. Filter or configure the client tool to only introspect configured schemas.

Example fix

// before (schema.xml)
<schema name="db1" ...>...</schema>
// after (add the schema the client references)
<schema name="db2" dataNode="dn1">...</schema>
Defensive patterns

Strategy: try-catch

Validate before calling

// check the referenced schema exists in Mycat config before sending SHOW
SchemaConfig sc = MycatServer.getInstance().getConfig().getSchemas().get(relSchema);
if (sc == null) throw new IllegalArgumentException("Schema not configured in Mycat: " + relSchema);

Try / catch

try { rrs = routeSystemInfo(showSql, sqlType, sc, ...); } catch (SQLSyntaxErrorException e) {
    if (e.getMessage().startsWith("not found schema : ")) {
        String missing = e.getMessage().substring("not found schema : ".length());
        log.warn("Client referenced unconfigured schema {}", missing);
    } else throw e;
}

Prevention

When it happens

Trigger: Running SHOW statements (e.g. from clients or GUI tools like MySQL Workbench/Navicat) whose query references a schema/database name absent from Mycat's schema.xml, or where the client sends a relation schema different from the current one.

Common situations: GUI tools enumerating all databases including ones not declared in schema.xml; clients connected to a database name that was never configured; typos or case mismatches in schema names; schemas dropped from config while clients still reference them.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/bef4986025fe9435. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/route/impl/DruidMycatRouteStrategy.java:624

		}
	}

	/**
	 * 分析 SHOW SQL
	 */
	@Override
	public RouteResultset analyseShowSQL(SchemaConfig schema,
			RouteResultset rrs, String stmt) throws SQLSyntaxErrorException {

		String[] fields = SchemaUtil.parseShowTable(stmt);
        if ("1".equals(fields[0])) {// show tables
			String relSchema = fields[3];
			String tableName = fields[8];
            //
            if (relSchema != null && !relSchema.equalsIgnoreCase(schema.getName())) {
                schema = MycatServer.getInstance().getConfig().getSchemas().get(relSchema);
                if (schema == null) {
                    throw new SQLSyntaxErrorException("not found schema : " + relSchema);
                }
            }
			// 2020/03/19 Ken.Li
			// if (StringUtils.isNotBlank(tableName) && tableName.indexOf("%") < 0) {
			if (StringUtils.isNotBlank(tableName) && tableName.indexOf("%") < 0 && !schema.getTables().isEmpty()) {
                TableConfig tableConfig = schema.getTables().get(tableName.toUpperCase());
                if (tableConfig != null) {
                    String dataNode = RouterUtil.getAliveRandomDataNode(tableConfig);
                    PhysicalDBNode dataNodeObj = MycatServer.getInstance().getConfig().getDataNodes().get(dataNode);
                    if (StringUtils.isNotBlank(dataNodeObj.getDatabase())) {
                        stmt = stmt.replaceAll(relSchema, dataNodeObj.getDatabase());
                    }
                    return RouterUtil.routeToSingleNode(rrs, dataNode, stmt);
                }
            }
            // remove db
            if (StringUtils.isNotBlank(relSchema)) {
				if(schema.getDataNode() !=null) {

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