[HIVE-22469] Lower Metastore DB Connection Pool Size in QTests

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.2.0
• Fix Version/s: 4.0.0, 4.0.0-alpha-1
• Component/s: Test, Tests
• Target Version/s: 4.0.0
• Flags: Patch
• Assignee: David Mollitor
• Reporter: David Mollitor
• Created: 07/Nov/19 16:57
• Updated: 22/Mar/22 08:54
• Resolved: 12/Nov/19 16:53

Description

Hive Metastore uses the 'HikariCP' database connection pool. The default number of connections to the database is 10. For the Qtests, connecting to a local DerbyDB, there need not be more than 4 connections. Anymore simply adds undo overhead and by looking at the QTest logs, I see a bunch of 'connection refused' from HikariCP. It may be the case that the standalone DB does not support that many concurrent connections anyway.

https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-MetaStore

I also unified all of the JDBC connection strings to ensure that each test is using an in-memory database.