logback dbappender performance
<configuration debug="true" scan="true">

    <property resource="log.properties" />

    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <!-- encoders are assigned the type ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>

    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${log.file.dir}/${project.artifactId}.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <!-- daily rollover -->
            <fileNamePattern>${project.artifactId}.%d{yyyy-MM-dd}.log</fileNamePattern>
            <!-- keep 30 days' worth of history -->
            <maxHistory>${log.file.rolling.history.days}</maxHistory>
        </rollingPolicy>

        <encoder>
            <pattern>%-4relative [%thread] %-5level %logger{35} - %msg%n</pattern>
        </encoder>
    </appender>

    <appender name="DB" class="ch.qos.logback.classic.db.DBAppender">
        <connectionSource class="ch.qos.logback.core.db.DataSourceConnectionSource">
            <dataSource class="com.mchange.v2.c3p0.ComboPooledDataSource">
                <driverClass>${log.db.driver}</driverClass>
                <jdbcUrl>jdbc:sybase:Tds:${log.db.server}:${log.db.port}/${log.db.name}</jdbcUrl>
                <serverName>${log.db.server}</serverName>
                <databaseName>${log.db.name}</databaseName>
                <user>${log.db.user}</user>
                <password>${log.db.password}</password>
            </dataSource>
        </connectionSource>
    </appender>

    <root level="INFO">
        <appender-ref ref="CONSOLE" />
        <appender-ref ref="FILE" />
    </root>

</configuration>

logback.xml -

<appender name="DB" class="ch.qos.logback.classic.db.DBAppender">

<filter class="ch.qos.logback.core.filter.EvaluatorFilter">
  <evaluator>
    <expression>if(logger.startsWith("com.forum.sub")&&level==ERROR)
    return true;
    return false;
    </expression>
  </evaluator>
  <OnMismatch>DENY</OnMismatch>
  <OnMatch>ACCEPT</OnMatch>
</filter>

<connectionSource class="ch.qos.logback.core.db.DataSourceConnectionSource">
        <dataSource class="com.mchange.v2.c3p0.ComboPooledDataSource">
          <driverClass>oracle.jdbc.driver.OracleDriver</driverClass>
          <jdbcUrl>jdbc:Oracle//127.0.0.1:1521/orcl</jdbcUrl>
          <user>SQA</user>
          <password>SQA</password>
        </dataSource>
      </connectionSource>
 </appender>

Error: -
ch.qos.logback.core.db.DataSourceConnectionSource@35bb0f - Could not get a connection to discover the dialect to use. java.sql.SQLException: Connections could not be acquired from the underlying database!
at java.sql.SQLException: Connections could not be acquired from the underlying database!
at  at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
at  at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529)
at  at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at  at ch.qos.logback.core.db.DataSourceConnectionSource.getConnection(DataSourceConnectionSource.java:72)
at  at ch.qos.logback.core.db.DataSourceConnectionSource.start(DataSourceConnectionSource.java:46)
at  at ch.qos.logback.core.joran.action.NestedComplexPropertyIA.end(NestedComplexPropertyIA.java:167)
at  at ch.qos.logback.core.joran.spi.Interpreter.callEndAction(Interpreter.java:315)
at  at ch.qos.logback.core.joran.spi.Interpreter.endElement(Interpreter.java:194)
at  at ch.qos.logback.core.joran.spi.Interpreter.endElement(Interpreter.java:180)
at  at ch.qos.logback.core.joran.spi.EventPlayer.play(EventPlayer.java:52)
at  at ch.qos.logback.core.joran.spi.Interpreter.play(Interpreter.java:332)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:126)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:93)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:52)
at  at ch.qos.logback.classic.util.ContextInitializer.configureByResource(ContextInitializer.java:77)
at  at ch.qos.logback.classic.util.ContextInitializer.autoConfig(ContextInitializer.java:150)
at  at org.slf4j.impl.StaticLoggerBinder.init(StaticLoggerBinder.java:85)
at  at org.slf4j.impl.StaticLoggerBinder.<clinit>(StaticLoggerBinder.java:55)
at  at org.slf4j.LoggerFactory.bind(LoggerFactory.java:121)
at  at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:111)
at  at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:268)
at  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:241)
at  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:254)
at  at com.forum.sub.LogbackTest.<clinit>(LogbackTest.java:16)
Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
at  at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
at  at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
at  at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
at  at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
at  ... 22 common frames omitted
WARN in ch.qos.logback.core.db.DataSourceConnectionSource@35bb0f - Connection does not    support GetGeneratedKey method and could not discover the dialect.
21:16:56,572 |-ERROR in ch.qos.logback.core.joran.spi.Interpreter@52:14 - RuntimeException in Action for tag [appender] java.lang.IllegalStateException: DBAppender cannot function if the JDBC driver does not support getGeneratedKeys method *and* without a specific SQL dialect
at java.lang.IllegalStateException: DBAppender cannot function if the JDBC driver does not support getGeneratedKeys method *and* without a specific SQL dialect
at  at ch.qos.logback.core.db.DBAppenderBase.start(DBAppenderBase.java:62)
at  at ch.qos.logback.classic.db.DBAppender.start(DBAppender.java:96)
at  at ch.qos.logback.core.joran.action.AppenderAction.end(AppenderAction.java:96)
at  at ch.qos.logback.core.joran.spi.Interpreter.callEndAction(Interpreter.java:315)
at  at ch.qos.logback.core.joran.spi.Interpreter.endElement(Interpreter.java:194)
at  at ch.qos.logback.core.joran.spi.Interpreter.endElement(Interpreter.java:180)
at  at ch.qos.logback.core.joran.spi.EventPlayer.play(EventPlayer.java:52)
at  at ch.qos.logback.core.joran.spi.Interpreter.play(Interpreter.java:332)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:126)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:93)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:52)
at  at ch.qos.logback.classic.util.ContextInitializer.configureByResource(ContextInitializer.java:77)
at  at ch.qos.logback.classic.util.ContextInitializer.autoConfig(ContextInitializer.java:150)
at  at org.slf4j.impl.StaticLoggerBinder.init(StaticLoggerBinder.java:85)
at  at org.slf4j.impl.StaticLoggerBinder.<clinit>(StaticLoggerBinder.java:55)
at  at org.slf4j.LoggerFactory.bind(LoggerFactory.java:121)
at  at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:111)
at  at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:268)
at  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:241)
at  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:254)
at  at com.forum.sub.LogbackTest.<clinit>(LogbackTest.java:16)