Oracle 10G vs Yukon

JustMax · Post by **JustMax** » 17 Feb 2004 20:34

начало здесь

http://forum.privet.com/posting.php?mode=quote&p=926204

Dmitry67 · Post by **Dmitry67** » 17 Feb 2004 20:39

http://forum.privet.com/viewtopic.php?t=48469&start=0

подробно описано tengizом, спасибо

JustMax · Post by **JustMax** » 17 Feb 2004 21:06

Прочитал - спасибо. Вопросы по версионности сняты (Видно я как-то умудрился пропустить тот топик

). Ну, посмотрим, чем ответит Оракл.

JustMax · Post by **JustMax** » 17 Feb 2004 21:36

Oracle Database 10g lets you guarantee undo retention. When you enable this option, the database never overwrites unexpired undo data--that is, undo data whose age is less than the undo retention period. This option is disabled by default, which means that the database can overwrite the unexpired undo data in order to avoid failure of DML operations if there is not enough free space left in the undo tablespace.

By enabling the guarantee option, you instruct the database not to overwrite unexpired undo data even if it means risking failure of currently active DML operations. Therefore, use caution when using this feature. A typical use of the guarantee option is when you want to ensure deterministic and predictable behavior of Flashback Query by guaranteeing the availability of the required undo data.

You enable the guarantee option by specifying the RETENTION GUARANTEE clause for the undo tablespace when it is created by either the CREATE DATABASE or CREATE UNDO TABLESPACE statement. Or, you can later specify this clause in an ALTER TABLESPACE statement. You do not guarantee that unexpired undo is preserved if you specify the RETENTION NOGUARANTEE clause.

You can use the DBA_TABLESPACES view to determine the RETENTION setting for the undo tablespace. A column named RETENTION will contain a value on GUARANTEE, NOGUARANTEE, or NOT APPLY (used for tablespaces other than the undo tablespace).

Борьба со snapshot too old.

В принципе имея flashback queries
, очистка undo space опираясь на минимальный SCN активных транзакций (примерно как это делает Yukon) не имеет смысла.

Dmitry67 · Post by **Dmitry67** » 17 Feb 2004 22:27

Решение в стиле Оракла кстати
Добавить тысяча первый параметр о котором должна болеть голова
Решение майкрософт тоже в их стиле, не настраивается ничего, мышина думает за тебя
Я иногда думаю а не лоббируют ли Oracle DBAs сложность настройки системы