What's the Best Database-Agnostic Query for Testing SQL Connection Health?

Database-Agnostic Test Queries for SQL Connections

Introduction

Maintaining active database connections is crucial for optimal application performance. Connection pooling libraries provide mechanisms to test connections for idleness, ensuring database connectivity. However, finding a database-agnostic test query that works seamlessly across different SQL databases can be challenging.

Question

What is an efficient and database-agnostic query that can be used to test SQL connections across various database providers?

Answer

After extensive research, it has been determined that there is no single query that works uniformly across all SQL databases. However, the following set of queries can be used based on the specific database provider:

• H2, MySQL, Microsoft SQL Server, PostgreSQL, SQLite, Hive:

  • SELECT 1

• Oracle:

  • SELECT 1 FROM DUAL

• HSQLDB:

  • SELECT 1 FROM any_existing_table WHERE 1=0
  • SELECT 1 FROM INFORMATION_SCHEMA.SYSTEM_USERS
  • CALL NOW()

• Apache Derby:

  • VALUES 1 or SELECT 1 FROM SYSIBM.SYSDUMMY1

• DB2:

  • SELECT 1 FROM SYSIBM.SYSDUMMY1

• Informix:

  • select count(*) from systables

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