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Questions

Questions and Answers

26.8.1:
Where can I find information on how to migrate from MySQL
4.1 to MySQL 5.0?

关于升级,请看 Section 2.3.16, “Upgrading MySQL”.
我们建议你升级的时候不要漏掉主要的版本,从一个主要版本升级到下一个主要版本,依此类推.这看起来比较复杂,不过却能减少时间和麻烦 - 升级过程中如果碰到麻烦了,则原因比较容易被找到,也许是你,也许是MySQL的支持 - 如果你有MySQL网络订购的话.

For detailed upgrade information, see
Section 2.3.16, “Upgrading MySQL”. We recommend that you do not skip
a major version when upgrading, but rather complete the
process in steps, upgrading from one major version to the
next in each step. This may seem more complicated, but it
will you save time and trouble — if you encounter
problems during the upgrade, their origin will be easier to
identify, either by you or — if you have a MySQL
Network subscription — by MySQL support.

26.8.2:
How has storage engine (table type) support changed in MySQL
5.0 from previous versions?

存储引擎发生了以下变化:

• MySQL 5.0中不再支持 ISAM 类型,现在可以使用 MyISAM 来代替它.想要把一个数据表 tblname 从 ISAM 类型转换为 MyISAM 类型,只需执行类似以下语句:

  ALTER TABLE tblname ENGINE=MYISAM;

• MySQL 5.0中删除了 MyISAM 类型表内部的 RAID.以前用它来解决文件系统不支持单个文件大小不能超过 2GB的问题.所有最新的文件系统都能支持大文件;另外,现在也可以用诸如 MERGE 或视图的方法来解决这个问题.

• VARCHAR 字段类型在所有的存储引擎中都会删除尾部的空格.

• MEMORY 类型表(以前叫做 HEAP 表) 也可以支持 VARCHAR 字段了.

Storage engine support has changed as follows:

• Support for ISAM tables was removed
  in MySQL 5.0 and you should now use the
  MyISAM storage engine in place of
  ISAM. To convert a table
  tblname from
  ISAM to MyISAM,
  simply issue a statement such as this one:

  ALTER TABLE tblname ENGINE=MYISAM;

• Internal RAID for
  MyISAM tables was also removed in
  MySQL 5.0. This was formerly used to allow large
  tables in file systems that did not support file sizes
  greater than 2GB. All modern file systems allow for
  larger tables; in addition, there are now other
  solutions such as MERGE tables and
  views.

• The VARCHAR column type now retains
  trailing spaces in all storage engines.

• MEMORY tables (formerly known as
  HEAP tables) can also contain
  VARCHAR columns.