MySQL engine connection fails in ADK ≥1.21.0 when using EventsCompactionConfig

[Priangshu-45]

Main Issue

In ADK version 1.21.0, MySQL database engine creation fails when EventsCompactionConfig is enabled. The same MySQL configuration works correctly in ADK 1.13.0, but event compaction is not available in that version. This appears to be a regression or an undocumented compatibility change related to database engine initialization.

---

To Reproduce

Minimal reproduction steps

1. Install ADK 1.21.0:

   pip install google-adk==1.21.0

2. Use the following minimal code:

   from google.adk.runtime import Runner
   from google.adk.runtime.config import EventsCompactionConfig
   
   runner = Runner(
       database_url="mysql+mysqlconnector://user:password@host:3306/db",
       events_compaction_config=EventsCompactionConfig()
   )

3. Start the application.

4. Observe the error:

   ValueError: Failed to create database engine for URL
   'mysql+mysqlconnector://user:password@host:3306/db'
   

Comparison

• ADK 1.13.0: MySQL connection works (EventsCompactionConfig not available)
• ADK 1.21.0: MySQL connection fails when EventsCompactionConfig is enabled

---

Expected behavior

MySQL connectivity that works in earlier ADK versions should continue to work when upgrading to newer versions, or the supported MySQL drivers for EventsCompactionConfig should be clearly documented with a clear and descriptive error message.

---

Screenshots

Code:

---

Desktop (please complete the following information)

• OS: Windows
• Python version (python -V): 3.10.x
• ADK version (pip show google-adk): 1.21.0

---

Model Information

• Model: gemini-2.5-flash

---

[wyf7107]

@DeanChensj , maybe a regression bug? Added planned tag, seems like a straightforward fix.

[Priangshu-45]

Could you please tell me where the planned tag is added.