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September 22, 2012 07:39
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transaction isolation level
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If your database supports setting the isolation level for a transaction, | |
you can set it like so: | |
Post.transaction(isolation: :serializable) do | |
# ... | |
end | |
Valid isolation levels are: | |
* `:read_uncommitted` | |
* `:read_committed` | |
* `:repeatable_read` | |
* `:serializable` | |
You should consult the documentation for your database to understand the | |
semantics of these different levels: | |
* http://www.postgresql.org/docs/9.1/static/transaction-iso.html | |
* https://dev.mysql.com/doc/refman/5.0/en/set-transaction.html | |
An `ActiveRecord::TransactionIsolationError` will be raised if: | |
* The adapter does not support setting the isolation level | |
* You are joining an existing open transaction | |
* You are creating a nested (savepoint) transaction | |
The mysql, mysql2 and postgresql adapters support setting the | |
transaction isolation level. However, support is disabled for mysql | |
versions below 5, because they are affected by a bug | |
(http://bugs.mysql.com/bug.php?id=39170) which means the isolation level | |
gets persisted outside the transaction. |
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