SqlLogger

SqlLogger is a callback interface that reports SQL execution events. Every statement calls either onSuccess or onError with details about the execution: rendered SQL, bound parameters, duration, and row count.

Key points:

• Synchronous — Callbacks run on the JDBC thread immediately after statement completion. Keep implementations fast; use a background thread for heavy I/O.
• SqlLogger.noop — Pre-built no-op instance that discards all events. Default when no custom logger is configured.

Core API

trait SqlLogger {
  def onSuccess(event: SqlLogger.SuccessEvent): Unit
  def onError(event: SqlLogger.ErrorEvent): Unit
}

Usage

Implement the trait to observe SQL execution:

import zio.blocks.sql.SqlLogger

val myLogger: SqlLogger = new SqlLogger {
  def onSuccess(event: SqlLogger.SuccessEvent): Unit =
    println(s"OK (${event.duration.toMillis}ms, ${event.rowCount} rows): ${event.sql}")

  def onError(event: SqlLogger.ErrorEvent): Unit =
    println(s"FAIL: ${event.error.getMessage}")
}
// myLogger: SqlLogger = repl.MdocSession$MdocApp0$$anon$1@1b9203b8

Pass the logger when creating a JdbcTransactor:

import zio.blocks.sql._

val dataSource: javax.sql.DataSource = ???
val myLogger: SqlLogger = SqlLogger.noop

val tx = new JdbcTransactor(() => dataSource.getConnection(), SqlDialect.PostgreSQL, myLogger)

Use the predefined no-op logger when you don't need logging:

import zio.blocks.sql._

val dataSource: javax.sql.DataSource = ???
val tx: JdbcTransactor = JdbcTransactor.fromDataSource(dataSource, SqlDialect.PostgreSQL)