DBAppender contains scripts for creating tables with columns with maximal length
 - for example renderedmessage is VARCHAR2(4000). However while appending
records length is not controlled, so if I try to append long log database throws
exception and nothing is logged.

The same problem as with rendered message is with writing stack trace. So I
extended your classes with mine, although I think this functionality should be
in base classes.

############## Repaired Log4JTrimmedLoggingEvent ################

package cz.corpus.f1.commons.log;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.log4j.spi.LocationInfo;
import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.spi.ThrowableInformation;

import java.util.Hashtable;
import java.util.Map;
import java.util.Set;

/**
 * @author Jan Novotný
 */
public class Log4JTrimmedLoggingEvent extends LoggingEvent {
    LoggingEvent original;

    public Log4JTrimmedLoggingEvent(LoggingEvent original) {
        this.original = original;
    }

    public boolean equals(Object rObject) {
        return original.equals(rObject);
    }

    public String getFQNOfLoggerClass() {
        return original.getFQNOfLoggerClass();
    }

    public Level getLevel() {
        return original.getLevel();
    }

    public LocationInfo getLocationInformation() {
        return original.getLocationInformation();
    }

    public Logger getLogger() {
        return original.getLogger();
    }

    public String getLoggerName() {
        return original.getLoggerName();
    }

    public Object getMDC(final String key) {
        return original.getMDC(key);
    }

    public void getMDCCopy() {
        original.getMDCCopy();
    }

    public Object getMessage() {
        return original.getMessage();
    }

    public String getNDC() {
        return original.getNDC();
    }

    public Map getProperties() {
        return original.getProperties();
    }

    public String getProperty(String key) {
        return original.getProperty(key);
    }

    public Set getPropertyKeySet() {
        return original.getPropertyKeySet();
    }

    public String getRenderedMessage() {
        String origMsg = original.getRenderedMessage();
        if(origMsg.length() > 3800){
        	return origMsg.substring(0, 3800) + " ... msg too long - trimed " +
(origMsg.length() - 3800) + " characters";
        }	
        return origMsg;
    }

    public long getSequenceNumber() {
        return original.getSequenceNumber();
    }

    public String getThreadName() {
        return original.getThreadName();
    }

    public ThrowableInformation getThrowableInformation() {
        return new
Log4JTrimmedThrowableInformation(original.getThrowableInformation());
    }

    public String[] getThrowableStrRep() {
        return new
Log4JTrimmedThrowableInformation(original.getThrowableInformation()).getThrowableStrRep();
    }

    public long getTimeStamp() {
        return original.getTimeStamp();
    }

    public int hashCode() {
        return original.hashCode();
    }

    public void initializeProperties() {
        original.initializeProperties();
    }

    public boolean locationInformationExists() {
        return original.locationInformationExists();
    }

    public void prepareForDeferredProcessing() {
        original.prepareForDeferredProcessing();
    }

    public void setFQNOfLoggerClass(String fqnOfLoggerClass) {
        original.setFQNOfLoggerClass(fqnOfLoggerClass);
    }

    public void setLevel(Level level) {
        original.setLevel(level);
    }

    public void setLocationInformation(LocationInfo li) {
        original.setLocationInformation(li);
    }

    public void setLogger(Logger logger) {
        original.setLogger(logger);
    }

    public void setLoggerName(String loggerName)
            throws IllegalStateException {
        original.setLoggerName(loggerName);
    }

    public void setMessage(Object message) {
        original.setMessage(message);
    }

    public void setNDC(String ndcString) {
        original.setNDC(ndcString);
    }

    public void setProperties(Hashtable properties) {
        original.setProperties(properties);
    }

    public void setProperty(String key, String value) {
        original.setProperty(key, value);
    }

    public void setRenderedMessage(String renderedMessage)
            throws IllegalStateException {
        original.setRenderedMessage(renderedMessage);
    }

    public void setSequenceNumber(long sequenceNumber) {
        original.setSequenceNumber(sequenceNumber);
    }

    public void setThreadName(String threadName)
            throws IllegalStateException {
        original.setThreadName(threadName);
    }

    public void setThrowableInformation(ThrowableInformation ti) {
        original.setThrowableInformation(ti);
    }

    public void setTimeStamp(long timeStamp) {
        original.setTimeStamp(timeStamp);
    }
}


############## Repaired Log4JTrimmedThrowableInformation ###############

package cz.corpus.f1.commons.log;

import org.apache.log4j.spi.ThrowableInformation;

/**
 * @author Jan Novotný
 */
public class Log4JTrimmedThrowableInformation extends ThrowableInformation {
    ThrowableInformation original;

    public Log4JTrimmedThrowableInformation(ThrowableInformation ti) {
        super(ti.getThrowableStrRep());
        original = ti;
    }

    public boolean equals(Object o) {
        return original.equals(o);
    }

    public Throwable getThrowable() {
        return original.getThrowable();
    }

    public String[] getThrowableStrRep() {
        String[] throwableStrRep = original.getThrowableStrRep();
        String[] result = new String[throwableStrRep.length];
        for (int i = 0; i < throwableStrRep.length; i++) {
            String msg = throwableStrRep[i];
            int lng = msg.length();
            if (msg != null && lng > 254) {
                msg = "..." + msg.substring(lng - 230, lng);
            }
            result[i] = msg;
        }
        return throwableStrRep;
    }
}