MyCATApache/Mycat-Server · error

ER_PARSE_ERROR

ER_PARSE_ERROR

Error message

msg == null ? e.getClass().getSimpleName() : msg

What it means

DruidMycatRouteStrategy.doExecute routes a multi-statement SQL through the Druid parser/router. If routing throws (parse error, unknown table, config problem), the exception is logged and its message — or the exception class simple name when the message is null — is sent to the client as an ER_PARSE_ERROR MySQL error. This is the generic 'your statement could not be routed' failure of the Druid-based strategy.

Solutions

  1. Look at the server log line ending with 'err:' to see the full stack trace of the real routing exception.
  2. Fix the SQL syntax to something Druid supports, or upgrade the Druid dependency for newer MySQL syntax support.
  3. Ensure the referenced tables/schemas/dataNodes exist in schema.xml with correct primaryKey settings.
  4. If the client message is just a class name (message was null), reproduce in tests to capture the actual NPE cause and fix the config/route logic.

Example fix

// before: SQL Druid cannot parse (MySQL 8 CTE variant)
WITH cte AS (SELECT ...) SELECT * FROM cte;
// after: rewrite with a subquery or upgrade Druid
SELECT * FROM (SELECT ...) AS cte;
Defensive patterns

Strategy: try-catch

Validate before calling

// check the statement targets configured tables before routing
for (String tbl : extractTables(sql)) {
  if (!mycatSchema.tablesContain(tbl)) throw new IllegalStateException("table not configured: " + tbl);
}

Try / catch

try {
  stmt.execute(sql);
} catch (SQLException e) {
  if (e.getErrorCode() == 1064 /* ER_PARSE_ERROR */) {
    logger.error("route/parse failed, check server log 'err:' line; sql={}", sql);
  }
}

Prevention

When it happens

Trigger: Executing SQL that Druid's parser cannot handle (unsupported syntax, MySQL 8 features, comments/hints Druid rejects), or routing throwing due to missing schema/table/primaryKey configuration; also e.getMessage() returning null (e.g. NPE) which degrades to the exception class name in the client error.

Common situations: Statements with newer MySQL syntax unsupported by the bundled Druid version, queries against tables absent from schema.xml, NPEs during routing producing 'NullPointerException' as the client-visible message, multi-statement strings where one clause fails.

Understand the failure class

Background: "query failed", "%w: SQL error" — wrapped database query errors in Go libraries explained — this error's family across 3 libraries.

Related errors

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/36987ef4efa2a59f. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/route/impl/DruidMycatRouteStrategy.java:363

			public void doExecute(List param) {
				sc.getSession2().setMiddlerResultHandler(null);
				String sqls = null;
				// 路由计算
				RouteResultset rrs = null;
				try {

					sqls = buildSql(statement,sqlselect,param);
					rrs = MycatServer
							.getInstance()
							.getRouterservice()
							.route(MycatServer.getInstance().getConfig().getSystem(),
									schema, sqlType,sqls.toLowerCase(), charset,sc );

				} catch (Exception e) {
					StringBuilder s = new StringBuilder();
					LOGGER.warn(s.append(this).append(sqls).toString() + " err:" + e.toString(),e);
					String msg = e.getMessage();
					sc.writeErrMessage(ErrorCode.ER_PARSE_ERROR, msg == null ? e.getClass().getSimpleName() : msg);
					return;
				}
				NonBlockingSession noBlockSession =  new NonBlockingSession(sc.getSession2().getSource());
				noBlockSession.setMiddlerResultHandler(null);
				//session的预编译标示传递
				noBlockSession.setPrepared(sc.getSession2().isPrepared());
				if (rrs != null) {
					noBlockSession.setCanClose(false);
					noBlockSession.execute(rrs, ServerParse.SELECT);
				}
			}
		} );
		sc.getSession2().setMiddlerResultHandler(middlerResultHandler);
		sc.getSession2().setCanClose(false);

		// 路由计算
		RouteResultset rrs = null;
		try {

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