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| Тема |
 Re: толкоз ли е умен координатора ? [re: Perin] |
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| Автор |
Perin (binary) |
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| Публикувано | 20.10.02 07:30 |
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Da ama ne. Popotarsih iz neta. Znachi tova che koordinatora e umen i manage-va niakolko transakcii tova dobre. Ama samite transaktnati resursi triabva da poddarjat protokol za two-phase commit (XA). Eto ot tuka cheta:
Eto malko citati:
A distributed transaction, sometimes referred to as a global transaction, is a set of two or more related transactions that must be managed in a coordinated way. The transactions that constitute a distributed transaction might be in the same database, but more typically are in different databases and often in different locations. Each individual transaction of a distributed transaction is referred to as a transaction branch.
For example, a distributed transaction might consist of money being transferred from an account in one bank to an account in another bank. You would not want either transaction committed without assurance that both will complete successfully.
In the JDBC 2.0 extension API, distributed transaction functionality is built on top of connection pooling functionality, described under "Connection Pooling". This distributed transaction functionality is also built upon the open XA standard for distributed transactions. (XA is part of the X/Open standard and is not specific to Java.)
XA functionality is usually isolated from a client application, being implemented instead in a middle-tier environment such as an application server.
In many scenarios, the application server and transaction manager will be together on the middle tier, possibly together with some of the application code as well.
Software that uses distributed transactions cannot use normal connection instance COMMIT, auto-commit, or ROLLBACK functionality, because all COMMIT or ROLLBACK operations in a distributed transaction must be coordinated. Any attempt to use the commit() or rollback() method or enable the auto-commit flag of a connection instance would result in a SQL exception.
When you use XA functionality, the transaction manager uses XA resource instances to prepare and coordinate each transaction branch and then to commit or roll back all transaction branches appropriately.
Taka che predishnite mi izkazvania che vsiaka transaktnata baza stava i za distributed sa palna boza. Vij dali InnoDB poddarja XA protokola - namerih tova vav FAQ-to na TUXEDO:
Does TUXEDO work with PostgreSQL, mySQL, under Linux 5.2, 6.0, 6.1?
Yes it does, categorically, for database queries and updates. You won’t be able to have TUXEDO coordinate your global transactions though, since these databases don’t support transactions, let alone XA transactions.
Eto i linka:
Samo che FAQ-to e ot 98-a godina, moje neshto da ima naprtaveno po vaprosa. Postgre opredeleno znam che poddarja transakcii. No ako poddarjaha XA sigurno shtiaha da trabiat ta vsichki da chuiat.
НЕ МЕ ЕБЕ КАК Е ВУТЕ, АЗ ГЛЕДАМ ДА СЪМ ДОБРЕ
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