本文深入探讨了在使用Hibernate时，配置hibernate.hbm2ddl.autoupdate可能导致的问题，即它不自动创建自定义索引（除了主键和外键索引）。文章详细解释了官方对于此配置设置的理解，并强调自动schema更新工具仅适用于开发环境，且无需在开发环境中创建索引，因为它们主要用于性能和可扩展性调整。
当hibernate的hbm2dll配置为
将会发现Hibernate不会为我们创建任何自定义的索引(不包括主键跟外键索引),不论你使用xml方式或者annotation进行声明配置
这个问题在Hibernate的JIRA多次出现，甚至有人专门为此发布了打了补丁的hibernate.jar
这个所谓的bug，在目前已发布的hibernate的版本中，一直都没有解决，或者说不予理睬(Gavin King个人认为这个不是bug)
这里引用hibernate 3.2.5版的jira
http://opensource.atlassian.com/projects/hibernate/browse/HHH-1012
引用Hibernate上官方的解释
The hibernate.hbm2ddl.auto=update setting doesn't create indexes
SchemaUpdate is activated by this configuration setting. SchemaUpdate is not really very powerful and comes without any warranties. For example, it does not create any indexes automatically. Furthermore, SchemaUpdate is only useful in development, per definition (a production schema is never updated automatically). You don't need indexes in development.
Hibernate doesn't generate the database indexes I want in the schema!
Automatic schema export (and update) by Hibernate tools is only useful in development. You never need indexes in development, they are purely for performance and scalability tuning in production systems. Production schemas are never automatically generated, at least not completely. A DBA adds indexes to the automatically generated schema during SQL tuning and testing of the application, before going into production with the (possibly automatically generated) base schema, and her handwritten optimized DDL. Also note that optimized DDL is highly vendor specific and totally dependent on the environment (SQL execution plans, tablespace configuration, caches, etc). Even if Hibernate developers would encourage you to automatically generate production-ready schemas (we don't, and we also don't like ad-hoc SQL tuning by throwing a bunch of indexes onto a schema), Hibernate could never offer such a feature.
hibernate.hbm2ddl.auto update
将会发现Hibernate不会为我们创建任何自定义的索引(不包括主键跟外键索引),不论你使用xml方式或者annotation进行声明配置
这个问题在Hibernate的JIRA多次出现，甚至有人专门为此发布了打了补丁的hibernate.jar
这个所谓的bug，在目前已发布的hibernate的版本中，一直都没有解决，或者说不予理睬(Gavin King个人认为这个不是bug)
这里引用hibernate 3.2.5版的jira
http://opensource.atlassian.com/projects/hibernate/browse/HHH-1012
引用Hibernate上官方的解释
引用
The hibernate.hbm2ddl.auto=update setting doesn't create indexes
SchemaUpdate is activated by this configuration setting. SchemaUpdate is not really very powerful and comes without any warranties. For example, it does not create any indexes automatically. Furthermore, SchemaUpdate is only useful in development, per definition (a production schema is never updated automatically). You don't need indexes in development.
Hibernate doesn't generate the database indexes I want in the schema!
Automatic schema export (and update) by Hibernate tools is only useful in development. You never need indexes in development, they are purely for performance and scalability tuning in production systems. Production schemas are never automatically generated, at least not completely. A DBA adds indexes to the automatically generated schema during SQL tuning and testing of the application, before going into production with the (possibly automatically generated) base schema, and her handwritten optimized DDL. Also note that optimized DDL is highly vendor specific and totally dependent on the environment (SQL execution plans, tablespace configuration, caches, etc). Even if Hibernate developers would encourage you to automatically generate production-ready schemas (we don't, and we also don't like ad-hoc SQL tuning by throwing a bunch of indexes onto a schema), Hibernate could never offer such a feature.
扫一扫
1万+
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
