ScalikeJDBC + Play Framework: Cannot change transaction read-only property error with secondary PostgreSQL DB

[harmeet24]

Hi everyone,

I'm working on a Play Framework application using ScalikeJDBC and PostgreSQL, and I’ve run into a persistent issue when using multiple database connections.
✅ Setup:

Play Framework (Scala) 2.9
ScalikeJDBC 4.x
PostgreSQL (Aurora)
HikariCP for connection pooling

I have two databases configured: db.default and db.analytics. The default DB works perfectly, but after some time, the secondary DB (db.analytics) throws the following exception:

org.postgresql.util.PSQLException: Cannot change transaction read-only property in the middle of a transaction.
	at org.postgresql.jdbc.PgConnection.setReadOnly(PgConnection.java:916)
	at com.zaxxer.hikari.pool.ProxyConnection.setReadOnly(ProxyConnection.java:410)
	at scalikejdbc.DBConnection.setReadOnly(DBConnection.scala:109)
	at scalikejdbc.DBConnection.newTx(DBConnection.scala:116)
	at scalikejdbc.NamedDB.localTx(NamedDB.scala:20)

🔍 Observations:

• The same code works fine with db.default.
  

• The error only occurs with db.analytics, especially after some idle time or under load.
  

• I suspect it’s related to connection reuse and session state not being reset.
  

application.conf configuration:

db.analytics {
  url = "jdbc:postgresql://${default-hostname}:${default-port}/user_database?socketTimeout=10&loginTimeout=2&connectTimeout=2&cancelSignalTimeout=2&tcpKeepAlive=true"
  username = "root"
  password = "test-password"
  driver = org.postgresql.Driver
  hikaricp.registerMbeans = true
  poolMaxSize = ${default-db-max-connections}
}



db.analytics {
  url = "jdbc:postgresql://${analytics-host}:${analytics-port}/user_database?socketTimeout=10&loginTimeout=2&connectTimeout=2&cancelSignalTimeout=2&tcpKeepAlive=true"
  username = "root"
  password = "test-password"
  driver = org.postgresql.Driver
  hikaricp.registerMbeans = true
  poolMaxSize = ${analytics-db-max-connections}
}

❓ Question:

• Why does this issue only affect the secondary DB and not db.default?
  

• Is there a better way to ensure connections are reset properly between uses?
  

• Any best practices for managing multiple DBs with ScalikeJDBC and HikariCP?
  

Any help or insights would be greatly appreciated!

Thanks 🙏

[mkurz]

For me this sounds like this has nothing to do with Play itself (but you never know).

It's hard for me to find out what's going on just by the config and the exception you provided.

My first guess this is either

• a configuration problem (maybe some jdbc flags?)
• the db's have a different set up
• a bug in ScalikeJDBC
• a bug in HikariCP
• a bug in the jdbc driver

Are you actually using the latest versions of ScalikeJDBC and HikariCP?

[mkurz]

Regarding the exception you posted - maybe a connection from the pool gets reused that either is currently in a transaction or a previous transaction of that connection/session was not closed correctly? If the later - the question is who is supposed to commit/rollback that transaction? Play, ScalikeJDBC or HikariCP?