tailieunhanh - MySQL Administrator's Bible- P10

MySQL Administrator's Bible- P10: Với tập trung đặc biệt vào việc phát hành lớn tiếp theo của MySQL, nguồn tài nguyên này cung cấp một khuôn khổ vững chắc cho bất cứ ai mới vào MySQL hoặc chuyển từ một nền tảng cơ sở dữ liệu, cũng như các quản trị MySQL kinh nghiệm. Các bộ đôi tác giả cao hồ sơ cung cấp bảo hiểm thiết yếu của các nguyên tắc cơ bản của phạm vi bảo hiểm cơ sở dữ liệu quản lý, bao gồm cả cách tiếp cận độc đáo MySQL của các tính năng cơ sở. | Storage Engines 11 Once this is done you can SELECT from the FEDERATED table and see the rows in the remote table. Limitations of FEDERATED tables Although FEDERATED tables can be extremely useful they do have some limitations. FEDERATED tables are non-transactional in nature regardless of the support that the remote table might have for transactions. In addition indexes are not always handled the same for the FEDERATED table as they are for the remote table. FEDERATED tables do not support index prefixes on CHAR VARCHAR TEXT or BLOB columns. There are instances where indexes are not used as expected. Though it is a fairly minor issue FEDERATED tables do not support the use of ALTER TABLE. To change the table definition of a FEDERATED table you must drop the table and re-create it. Even with these limitations the FEDERATED engine can be very useful when remote data access is needed. NDB storage engine The NDB storage engine is used to build a MySQL Cluster. MySQL Cluster is a shared-nothing highly available system. MySQL Cluster is designed to avoid a single point of failure. A cluster will contain one or more SQL nodes traditional MySQL Servers one or more data nodes and one or more management servers. For more information about MySQL Cluster see Chapter 22. Feature summary Built to provide high availability with redundant sets of data for node failure scenarios. Transactional support. No foreign key support. Row-level locking. Operates either entirely in memory or supports on-disk storage of data columns. Indexes must always be stored in memory. Beginning with MySQL Server version the standard binaries built by Sun Microsystems will not include the NDB storage engine. Though it is still available with the source code for now the code for the NDB storage engine will not be updated to keep pace with changes in the NDB storage engine. If you need to use the NDB storage engine use the MySQL Cluster server instead of MySQL Server. Archive storage engine The .