如何在UIB中设置Firebird数据库的事务隔离级别？
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本文共计1023个文字，预计阅读时间需要5分钟。
根据提供的文档，Firebird数据库中有四个事务隔离级别。然而，在UIB库（TUIBTransaction）中没有明确的隔离级别选项。尽管如此，有多个交易选项可以选择。
如何使用这些选项？以下是一些建议：
1. 理解UIB库选项：查看UIB库的文档或帮助文件，了解每个交易选项的含义和影响。
2. 参考示例代码：查找使用UIB库的示例代码，看其他开发者是如何处理事务隔离的。
3. 分析交易选项：分析UIB库提供的交易选项，例如： - `CommitMode`：控制事务提交的模式。 - `IsolationLevel`：设置事务的隔离级别，尽管可能没有直接的选项，但可能通过其他方式间接实现。
4. 测试不同选项：尝试不同的交易选项，观察对隔离级别的影响。
5. 考虑文件：检查是否有相关的配置文件或设置，可能会影响交易选项或隔离级别。
6. 调整隔离级别：根据您的需求和观察到的行为，调整交易选项以尝试达到期望的隔离级别。
以下是一个简化的示例代码片段，展示如何使用UIB库设置事务提交模式：
pascalvar T: TUIBTransaction;begin T :=TUIBTransaction.Create(nil); try T.CommitMode :=cmManual; // 或其他合适的提交模式
// 执行数据库操作
T.Commit; // 手动提交事务 finally T.Free; end;end;
请根据您的具体情况调整代码和策略。
根据 documents,Firebird中有四个事务隔离级别.但是,据我所知, uib库(TUIBTransaction)中没有明确的隔离级别选择,但是有很多交易选项.我该怎么用？某处有文件吗？ 这些选项将改变隔离级别.正如@Arioch在其简短评论中所说,您可以更改隔离级别,更改TTransParams类型的属性选项.这是一组TTransParam,如下所示.// Transaction parameters TTransParam = ( { prevents a transaction from accessing tables if they are written to by other transactions.} tpConsistency, { allows concurrent transactions to read and write shared data. } tpConcurrency, { Concurrent, shared access of a specified table among all transactions. } {$IFNDEF FB_21UP} tpShared, { Concurrent, restricted access of a specified table. } tpProtected, tpExclusive, {$ENDIF} { Specifies that the transaction is to wait until the conflicting resource is released before retrying an operation [Default]. } tpWait, { Specifies that the transaction is not to wait for the resource to be released, but instead, should return an update conflict error immediately. } tpNowait, { Read-only access mode that allows a transaction only to select data from tables. } tpRead, { Read-write access mode of that allows a transaction to select, insert, update, and delete table data [Default]. } tpWrite, { Read-only access of a specified table. Use in conjunction with tpShared, tpProtected, and tpExclusive to establish the lock option. } tpLockRead, { Read-write access of a specified table. Use in conjunction with tpShared, tpProtected, and tpExclusive to establish the lock option [Default]. } tpLockWrite, tpVerbTime, tpCommitTime, tpIgnoreLimbo, { Unlike a concurrency transaction, a read committed transaction sees changes made and committed by transactions that were active after this transaction started. } tpReadCommitted, tpAutoCommit, { Enables an tpReadCommitted transaction to read only the latest committed version of a record. } tpRecVersion, tpNoRecVersion, tpRestartRequests, tpNoAutoUndo {$IFDEF FB20_UP} ,tpLockTimeout {$ENDIF} );
由于Interbase 6.0代码“opensourced”,API的文档没有太大变化.因此,如果您想要了解其中任何一个,您正在查找的文档都在Interbase手册中.
你可以在这里得到它们www.firebirdsql.org/en/reference-manuals/
下面我在link中引用安·哈里森来快速解释一下常用的选项：
isc_tpb_consistency can cause performance problems due the fact that it’s locking tables and possibly excluding concurrent access.
isc_tpb_concurrency is the design center for Firebird. Readers don’t
block writers, writers don’t block readers, and both get a consistent
view of the database.isc_tpb_read_committed + isc_tpb_rec_version + isc_tbp_read_only give
inconsistent results and occasionally produces an error on a blob
read*, but unlike other modes, it does not block garbage collection so
it’s a good mode for long running read transactions that don’t have to
get the “right” answer.isc_tpb_read_committeed + isc_tpb_rec_version has the same performance
as isc_tpb_concurrency, but gets inconsistent results – the same query
run twice in the same transaction may return different rows.isc_tpb_read_committed + isc_tpb_no_rec_version + isc_tpb_wait is
slower than other modes because it will wait for a change to be
commited rather than reading the newest committed version. Like all
variants of isc_tpb_read_committed, it does not produce consistent
results.isc_tpb_read_committed + isc_tpb_no_rec_version + isc_tpb_no_wait
gives lots and lots of deadlock errors because every time a reader
encounters a record that’s being changed, it returns an error.
注意：我希望您可以看到,除了参数名称不同之外,如果删除“isc_tpb_”部分并不难理解.
本文共计1023个文字，预计阅读时间需要5分钟。
根据提供的文档，Firebird数据库中有四个事务隔离级别。然而，在UIB库（TUIBTransaction）中没有明确的隔离级别选项。尽管如此，有多个交易选项可以选择。
如何使用这些选项？以下是一些建议：
1. 理解UIB库选项：查看UIB库的文档或帮助文件，了解每个交易选项的含义和影响。
2. 参考示例代码：查找使用UIB库的示例代码，看其他开发者是如何处理事务隔离的。
3. 分析交易选项：分析UIB库提供的交易选项，例如： - `CommitMode`：控制事务提交的模式。 - `IsolationLevel`：设置事务的隔离级别，尽管可能没有直接的选项，但可能通过其他方式间接实现。
4. 测试不同选项：尝试不同的交易选项，观察对隔离级别的影响。
5. 考虑文件：检查是否有相关的配置文件或设置，可能会影响交易选项或隔离级别。
6. 调整隔离级别：根据您的需求和观察到的行为，调整交易选项以尝试达到期望的隔离级别。
以下是一个简化的示例代码片段，展示如何使用UIB库设置事务提交模式：
pascalvar T: TUIBTransaction;begin T :=TUIBTransaction.Create(nil); try T.CommitMode :=cmManual; // 或其他合适的提交模式
// 执行数据库操作
T.Commit; // 手动提交事务 finally T.Free; end;end;
请根据您的具体情况调整代码和策略。
根据 documents,Firebird中有四个事务隔离级别.但是,据我所知, uib库(TUIBTransaction)中没有明确的隔离级别选择,但是有很多交易选项.我该怎么用？某处有文件吗？ 这些选项将改变隔离级别.正如@Arioch在其简短评论中所说,您可以更改隔离级别,更改TTransParams类型的属性选项.这是一组TTransParam,如下所示.// Transaction parameters TTransParam = ( { prevents a transaction from accessing tables if they are written to by other transactions.} tpConsistency, { allows concurrent transactions to read and write shared data. } tpConcurrency, { Concurrent, shared access of a specified table among all transactions. } {$IFNDEF FB_21UP} tpShared, { Concurrent, restricted access of a specified table. } tpProtected, tpExclusive, {$ENDIF} { Specifies that the transaction is to wait until the conflicting resource is released before retrying an operation [Default]. } tpWait, { Specifies that the transaction is not to wait for the resource to be released, but instead, should return an update conflict error immediately. } tpNowait, { Read-only access mode that allows a transaction only to select data from tables. } tpRead, { Read-write access mode of that allows a transaction to select, insert, update, and delete table data [Default]. } tpWrite, { Read-only access of a specified table. Use in conjunction with tpShared, tpProtected, and tpExclusive to establish the lock option. } tpLockRead, { Read-write access of a specified table. Use in conjunction with tpShared, tpProtected, and tpExclusive to establish the lock option [Default]. } tpLockWrite, tpVerbTime, tpCommitTime, tpIgnoreLimbo, { Unlike a concurrency transaction, a read committed transaction sees changes made and committed by transactions that were active after this transaction started. } tpReadCommitted, tpAutoCommit, { Enables an tpReadCommitted transaction to read only the latest committed version of a record. } tpRecVersion, tpNoRecVersion, tpRestartRequests, tpNoAutoUndo {$IFDEF FB20_UP} ,tpLockTimeout {$ENDIF} );
由于Interbase 6.0代码“opensourced”,API的文档没有太大变化.因此,如果您想要了解其中任何一个,您正在查找的文档都在Interbase手册中.
你可以在这里得到它们www.firebirdsql.org/en/reference-manuals/
下面我在link中引用安·哈里森来快速解释一下常用的选项：
isc_tpb_consistency can cause performance problems due the fact that it’s locking tables and possibly excluding concurrent access.
isc_tpb_concurrency is the design center for Firebird. Readers don’t
block writers, writers don’t block readers, and both get a consistent
view of the database.isc_tpb_read_committed + isc_tpb_rec_version + isc_tbp_read_only give
inconsistent results and occasionally produces an error on a blob
read*, but unlike other modes, it does not block garbage collection so
it’s a good mode for long running read transactions that don’t have to
get the “right” answer.isc_tpb_read_committeed + isc_tpb_rec_version has the same performance
as isc_tpb_concurrency, but gets inconsistent results – the same query
run twice in the same transaction may return different rows.isc_tpb_read_committed + isc_tpb_no_rec_version + isc_tpb_wait is
slower than other modes because it will wait for a change to be
commited rather than reading the newest committed version. Like all
variants of isc_tpb_read_committed, it does not produce consistent
results.isc_tpb_read_committed + isc_tpb_no_rec_version + isc_tpb_no_wait
gives lots and lots of deadlock errors because every time a reader
encounters a record that’s being changed, it returns an error.
注意：我希望您可以看到,除了参数名称不同之外,如果删除“isc_tpb_”部分并不难理解.