Spring Data JPA with Hikari: Why is hikari auto-commit property set to 'true'?-CodePudding

Spring Data JPA or Hibernate have by default auto-commit set to false. This sounds reasonable as these frameworks work with entities and an update to an entity could involve updates to multiple tables through multiple SQL queries. So by setting auto-commit to false and explicitly controlling a transaction these frameworks ensure that a change to entity is atomic and consistent.

But now Hikari is the default connection pool provider for spring data jpa, and on looking at application logs I see hikari sets auto-commit to true for the connection pool.

2021-10-24 11:30:07.815 DEBUG   [restartedMain] com.zaxxer.hikari.HikariConfig||HikariConfig.logConfiguration:1135: autoCommit................................true

Any explanation of why this is set so and does this effect transactions(I don't think it effects transactions as each transaction might again set auto-commit to false and thus take over when to commit the transaction.)

Edit - following @ken-chan answer and discussion.
For projects using spring data jpa with @Transactional (with 100% Hiberante), changing hikaris connection pool settings to auto-commit=false should give performance benefit. Please see answer and subsequent discussion for more details.

CodePudding user response：

I think Hikari just follows the default auto-commit value (i.e. true) defined by JDBC in order to align with its default behaviour .(See this)

And your guess is correct , the framework will take care to configure the necessary auto-commit value of the JDBC Connection such that it can do the transactional stuff over multiple JDBC Statement.

For example in Spring @Transactionl using JDBC , the following codes show that if the auto-commit is enabled , it will disable it before executing any transactional codes. It also will re-enable it after completing the transaction.

// Switch to manual commit if necessary. This is very expensive in some JDBC drivers,
// so we don't want to do it unnecessarily (for example if we've explicitly
// configured the connection pool to set it already).
if (con.getAutoCommit()) {
    txObject.setMustRestoreAutoCommit(true);
    if (logger.isDebugEnabled()) {
        logger.debug("Switching JDBC Connection ["   con   "] to manual commit");
    }
    con.setAutoCommit(false);
}