压测的时候报错

执行./runBenchmark.sh mysql_1000w.properties报错
报错内容如下：

08:58:52,889 [Thread-3] ERROR  jTPCCTData : Unexpected SQLException in STOCK_LEVEL
08:58:52,889 [Thread-3] ERROR  jTPCCTData : Every derived table must have its own alias
java.sql.SQLSyntaxErrorException: Every derived table must have its own alias
        at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120)
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
        at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953)
        at com.mysql.cj.jdbc.ClientPreparedStatement.executeQuery(ClientPreparedStatement.java:1009)
        at jTPCCTData.executeStockLevel(jTPCCTData.java:2110)
        at jTPCCTData.execute(jTPCCTData.java:205)
        at jTPCCTerminal.executeTransactions(jTPCCTerminal.java:194)
        at jTPCCTerminal.run(jTPCCTerminal.java:96)
        at java.lang.Thread.run(Thread.java:748)
08:58:52,929 [Thread-2] ERROR  jTPCCTData : Unexpected SQLException in STOCK_LEVEL
08:58:52,929 [Thread-2] ERROR  jTPCCTData : Every derived table must have its own alias
java.sql.SQLSyntaxErrorException: Every derived table must have its own alias
        at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120)
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
        at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953)
        at com.mysql.cj.jdbc.ClientPreparedStatement.executeQuery(ClientPreparedStatement.java:1009)
        at jTPCCTData.executeStockLevel(jTPCCTData.java:2110)
        at jTPCCTData.execute(jTPCCTData.java:205)
        at jTPCCTerminal.executeTransactions(jTPCCTerminal.java:194)
        at jTPCCTerminal.run(jTPCCTerminal.java:96)
        at java.lang.Thread.run(Thread.java:748)

错误分析

可以看到jTPCCTData.executeStockLevel方法报错，查看此方法内容
该错误与SQL查询有关，这里提示的是"Every derived table must have its own alias"，也就是说每个派生表必须有自己的别名。这种错误通常在我们在SQL查询中使用子查询或者join操作，但没有给子查询或者join的表提供别名时出现。

    private void executeStockLevel(Logger log, jTPCCConnection db)
	throws Exception
    {
	PreparedStatement       stmt;
	ResultSet               rs;

	try
	{
	    stmt = db.stmtStockLevelSelectLow;
	    stmt.setInt(1, stockLevel.w_id);
	    stmt.setInt(2, stockLevel.threshold);
	    stmt.setInt(3, stockLevel.w_id);
	    stmt.setInt(4, stockLevel.d_id);
	    rs = stmt.executeQuery();
	    if (!rs.next())
	    {
		throw new Exception("Failed to get low-stock for" +
				    " W_ID=" + stockLevel.w_id +
				    " D_ID=" + stockLevel.d_id);
	    }
	    stockLevel.low_stock = rs.getInt("low_stock");
	    rs.close();

	    db.commit();
	}
	catch (SQLException se)
	{
	    log.error("Unexpected SQLException in STOCK_LEVEL");
	    for (SQLException x = se; x != null; x = x.getNextException())
		log.error(x.getMessage());
	    se.printStackTrace();

	    try
	    {
		db.rollback();
	    }
	    catch (SQLException se2)
	    {
		throw new Exception("Unexpected SQLException on rollback: " +
				se2.getMessage());
	    }
	}
	catch (Exception e)
	{
	    try
	    {
		db.rollback();
	    }
	    catch (SQLException se2)
	    {
		throw new Exception("Unexpected SQLException on rollback: " +
				se2.getMessage());
	    }
	    throw e;
	}
    }

我们需要找到db.stmtStockLevelSelectLow这个PreparedStatement的定义部分，也就是对应的SQL语句是什么，才能对其进行修改。
找到那个SQL查询语句后，你需要检查这个查询中的每个子查询或者JOIN的表是否都有别名。如果没有，需要为其添加别名。
可以看到PG和Oracle的SQL定义都带了 AS L，将MySQL部分加上即可

	    default:
		stmtStockLevelSelectLow = dbConn.prepareStatement(
		    "SELECT count(*) AS low_stock FROM (" +
		    "    SELECT s_w_id, s_i_id, s_quantity " +
		    "        FROM bmsql_stock " +
		    "        WHERE s_w_id = ? AND s_quantity < ? AND s_i_id IN (" +
		    "            SELECT ol_i_id " +
		    "                FROM bmsql_district " +
		    "                JOIN bmsql_order_line ON ol_w_id = d_w_id " +
		    "                 AND ol_d_id = d_id " +
		    "                 AND ol_o_id >= d_next_o_id - 20 " +
		    "                 AND ol_o_id < d_next_o_id " +
		    "                WHERE d_w_id = ? AND d_id = ? " +
		    "        ) " +
		    "    ) AS L");
		break;
	}

重新编译

编译后，可以正常进行压测

11:21:28,205 [main] INFO   jTPCC : Term-00, 
progress: 0.0, tpmTOTAL: 7500.0, tpmC: 0.0
progress: 1.0, tpmTOTAL: 16303.7, tpmC: 7732.3
progress: 2.0, tpmTOTAL: 18422.4, tpmC: 8806.8
progress: 3.0, tpmTOTAL: 18573.8, tpmC: 8957.0
progress: 4.0, tpmTOTAL: 18800.6, tpmC: 8650.7