当使用 MySQL 数据库时,在 JDBC 连接字符串中加入 useCursorFetch=true,并结合设置合适的 fetchSize,可以避免因一次性加载过多数据导致的内存溢出问题。注意,此配置仅对 MySQL 数据库有效。 如果不设置 useCursorFetch=true 这个配置,仅使用之前提到的那些配置(如设置 defaultFetchSize、分页
"Gives the JDBC driver a hint as to the number of rows that should be fetched from the database when more rows are needed. The number of rows specified affects only result sets created using this statement. If the value specified is zero, then the hint is ignored. The default value is ...
Use Avro Logical Types(使用Avro逻辑类型)false true false 是否对DECIMAL/NUMBER, DATE, TIME 和 TIMESTAMP 列使用Avro逻辑类型。Default Decimal Precision(Decimal数据类型位数)10 当 DECIMAL/NUMBER 数据类型转换成Avro类型数据时,指定的数据位数。Default Decimal Scale(Decimal 数据类型小数位数)0 当 DECIMAL/NUMBER...
"Gives the JDBC driver a hint as to the number of rows that should be fetched from the database when more rows are needed. The number of rows specified affects only result sets created using this statement. If the value specified is zero, then the hint is ignored. The default value is ...
Seems the default fetch size is 32. Don’t know much about this database as I don’t have this database server. You can change default fetch size by through connection property “block size”. Important note to consider when tuning fetch size: ...
DBI connect('None;host=None;port=None;charset=utf8mb4;mysql_read_default_group=client','None',...) failed: Unknown MySQL server host 'None' (2) at /usr/local/bin/pt-archiver line 2525. 五.主要参考资料 1.MySQL数据归档实战-Python和pt-archiver的强强结合 https://blog.csdn.net/n88lpo/...
虽然SQL查询优化的技术有很多,但是大方向上完全可以分成物理查询优化和逻辑查询优化两大块。 ①:物理查询优化是通过索引和表连接方式等技术来进行优化,这里重点需要掌握索引的使用。 ②:逻辑查询优化就是通过SQL等价变换提升查询效率,直白一点就是说,换一种查询写法执行效率可能更高。
mysql_set_local_infile_default() mysql_set_local_infile_handler() mysql_set_server_option() mysql_shutdown() mysql_sqlstate() mysql_ssl_set() mysql_stat() mysql_store_result() mysql_thread_id() mysql_use_result() mysql_warning_count() C API Prepared Statement Interface...
An array of unsigned long integers representing the size of each column (not including any terminating null bytes).NULLif an error occurred. Errors mysql_fetch_lengths()is valid only for the current row of the result set. It returnsNULLif you call it before callingmysql_fetch_row()or after ...
c1` int DEFAULT NULL, `c2` int DEFAULT NULL, `create_time` timestamp NOT NULL DEFAULT ...