为什么 Hibernate 仅在事务内自动刷新？
这种行为背后的理由是什么？
如果由于某种原因我在事务之外执行两个合适的操作（不推荐，我知道！）并且我已将 Hibernate 配置为自动刷新，那么如果第二个操作我期望它会自动刷新应该触发自动刷新（例如 list、iterate 或 executeUpdate）。
如果不是对 autoFlushIfRequried 方法的第二行进行显式检查，这正是会发生的情况：
protected boolean autoFlushIfRequired(Set querySpaces) throws HibernateException {
errorIfClosed();
if ( ! isTransactionInProgress() ) {
// do not auto-flush while outside a transaction
return false;
}
AutoFlushEvent event = new AutoFlushEvent(querySpaces, this);
AutoFlushEventListener[] autoFlushEventListener = listeners.getAutoFlushEventListeners();
for ( int i = 0; i < autoFlushEventListener.length; i++ ) {
autoFlushEventListener[i].onAutoFlush(event);
}
return event.isFlushRequired();
}
更新：谢谢 axtavt 用于查找导致此更改的 Hibernate 问题（在 3.2 中）：FlushMode.AUTO ->在事务外提交。
相关问题仍然悬而未决：在 FlushMode.MANUAL/ 的情况下延迟 IDENTITY 插入/从来没有，但是这两个讨论都没有提供“在事务之外操作时，FlushMode.AUTO 是一件坏事”的理由。
What is the rationale behind this behavior?
If for some reason I execute two suitable operations outside a transaction (not recommended, I know!) and I've configured Hibernate to auto-flush, I would expect it to auto-flush if the second operation is one that should trigger an auto-flush (like list, iterate, or executeUpdate).
That's exactly what would happen, if not for the explicit check on the second line of the autoFlushIfRequried method:
protected boolean autoFlushIfRequired(Set querySpaces) throws HibernateException {
errorIfClosed();
if ( ! isTransactionInProgress() ) {
// do not auto-flush while outside a transaction
return false;
}
AutoFlushEvent event = new AutoFlushEvent(querySpaces, this);
AutoFlushEventListener[] autoFlushEventListener = listeners.getAutoFlushEventListeners();
for ( int i = 0; i < autoFlushEventListener.length; i++ ) {
autoFlushEventListener[i].onAutoFlush(event);
}
return event.isFlushRequired();
}
Update: Thank you axtavt for finding the Hibernate issue that prompted this change (in 3.2): FlushMode.AUTO -> COMMIT when outside a transaction.
A related issue is still open: delay IDENTITY insertions in the case of FlushMode.MANUAL/NEVER, but neither discussion provides the rationale for saying "When operating outside a transaction, FlushMode.AUTO is a bad thing."
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因为
FlushMode的文档说所以，auto 并不意味着你所想的那样。可以说，这个名称选择得不好，但这并不意味着每次会话操作后都会进行刷新。因此，它与 JDBC 的自动提交不同，后者在 JDBC 语句之后进行提交。
Because the docummentation for
FlushModesaysSo, auto doesn't mean what you think it means. The name is, arguably, badly chosen, but it doesn't mean a flush is made after each session operation. It's thus not similar to JDBC's autocommit, which makes a commit after ever JDBC statement.