Aggarwal-Raghav opened a new pull request, #6917: URL: https://github.com/apache/hive/pull/6917
### What changes were proposed in this pull request? 1. Set Default HikariCP Pool Isolation to `READ_COMMITTED`: In HikariCPDataSourceProvider, set the default pool isolation level to TRANSACTION_READ_COMMITTED if not explicitly configured by the user. 2. Upgrade HikariCP: Upgraded HikariCP from **4.0.3 to 7.1.0** 3. Dependency Cleanup: Removed the unused `com.zaxxer:HikariCP` dependency from metastore-common/pom.xml to prevent leaking it onto client classpaths. ### Why are the changes needed? - All Metastore operations (ACID TxnHandler and DataNucleus JDO) run at READ_COMMITTED. - Previously, HikariCPDataSourceProvider left pool isolation unconfigured, which defaults to **REPEATABLE_READ on MySQL and MariaDB backends.** - This mismatch caused Spring's transaction manager to issue two extra network round-trips on every single transaction: changing to `READ COMMITTED` at transaction start and reverting to `REPEATABLE READ` at completion. - Setting the pool default to READ_COMMITTED initializes connections once at startup, completely eliminating both round-trips from every transaction path. ### Does this PR introduce _any_ user-facing change? NO ### How was this patch tested? Wrote Junit and local mac testing to validate the new expected behaviour -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
