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在执行查询时,Mysql默认把结果全部load到内存后再返回(这种模式可理解为Oracle的ALL_ROWS优化模式),如果表数据量太大的话,会导致内存溢出。 1.在mysql console连接数据库时: 加入-q选项,mysql -h hostname -u root -p -q 2.在jdbc连接数据库时: 在连接串中加入 useCursorFetch =true 在创建的语句中,加入 setFetchSize,如 stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY, java.sql.ResultSet.CONCUR_READ_ONLY); stmt.setFetchSize(Integer.MIN_VALUE); 注意: The Integer.MIN_VALUE is used by the MySQL driver as a signal to switch to streaming result set mode. It is not used as a value. See the documentation, under "Resultset". In summary: By default, ResultSets are completely retrieved and stored in memory. You can tell the driver to stream the results back one row at a time by setting stmt.setFetchSize(Integer.MIN_VALUE); (in combination with a forward-only, read-only result set). 来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/6906/viewspace-2086751/,如需转载,请注明出处,否则将追究法律责任。
转载于:http://blog.itpub.net/6906/viewspace-2086751/