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https://issues.apache.org/jira/browse/CAY-2954?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrus Adamchik updated CAY-2954:
---------------------------------
Description:
Cayenne surrounds every DB interaction with a transaction. This doesn't make
sense for single select operations (the only case where it would is long
running externally managed transactions, where selects should see uncommitted
DB state produced by prior changes; though should be handled at the DataSource
level).
Per our benchmarks (see below), running selects in an auto-commit mode produces
significant performance benefits (for the app and the DB both).
So let's bypass implicit transactions when we can. Since Cayenne has no idea
whether the query requires a tx or not, the indicator should be provided by the
query itself ({{{}q.getMetadata().isReadOnly(){}}}). Most queries know whether
they are "read-only" or not. For those that don't (such as ProcedureQuery) it
will default to "false".
h2. Upgrade Notes
* Transaction listeners will no long receive begin/commit/rollback events.
That's a breaking change, but also looks like the correct thing to do.
was:
Cayenne surrounds every DB interaction with a transaction. This doesn't make
sense for single select operations (the only case where it would is long
running externally managed transactions, where selects should see uncommitted
DB state produced by prior changes; though should be handled at the DataSource
level).
Per our benchmarks (see below), running selects in an auto-commit mode
propduces significant performance benefits (for the app and the DB both).
So let's bypass implicit transactions when we can. Since Cayenne has no idea
whether the query requires a tx or not, the indicator should be provided by the
query itself ({{{}q.getMetadata().isReadOnly(){}}}). Most queries know whether
they are "read-only" or not. For those that don't (such as ProcedureQuery) it
will default to "false".
h2. Upgrade Notes
* Transaction listeners will no long receive begin/commit/rollback events.
That's a breaking change, but also looks like the correct thing to do.
> Don't wrap selecting queries in transactions
> --------------------------------------------
>
> Key: CAY-2954
> URL: https://issues.apache.org/jira/browse/CAY-2954
> Project: Cayenne
> Issue Type: Improvement
> Reporter: Andrus Adamchik
> Assignee: Andrus Adamchik
> Priority: Major
>
> Cayenne surrounds every DB interaction with a transaction. This doesn't make
> sense for single select operations (the only case where it would is long
> running externally managed transactions, where selects should see uncommitted
> DB state produced by prior changes; though should be handled at the
> DataSource level).
> Per our benchmarks (see below), running selects in an auto-commit mode
> produces significant performance benefits (for the app and the DB both).
> So let's bypass implicit transactions when we can. Since Cayenne has no idea
> whether the query requires a tx or not, the indicator should be provided by
> the query itself ({{{}q.getMetadata().isReadOnly(){}}}). Most queries know
> whether they are "read-only" or not. For those that don't (such as
> ProcedureQuery) it will default to "false".
> h2. Upgrade Notes
> * Transaction listeners will no long receive begin/commit/rollback events.
> That's a breaking change, but also looks like the correct thing to do.
>
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