Help for diagnosing and resolving any Content Services issues that you might encounter.

For additional help, refer to the following:

Set log levels

The file lets you configure logging levels to provide debugging information when troubleshooting. To set up logging policies, you must prepend log4j.logger to the class name you want to log to, and set the logging level. You can set the log level dynamically using the JMX client.

When using log4j, you should:

  • Keep local customizations and licenses outside of the web application. For example, in the extension directory:

  • The supplied configuration files should be stored or installed within the web application. For example:


Note: A file should not be packaged as a part of any product.

Logging uses the Log4J HierarchyDynamicMBean.

Note: Log levels are not cluster-aware. If needed, the log level change will need to be applied to each machine. Some consoles (for example, JManage) can provide basic facilities for accessing each machine in an application cluster.

  • Editable attributes are a dynamic list of loggers with the logLevel attribute, which can be changed to OFF, FATAL, ERROR, WARN, INFO, DEBUG or TRACE (editable).

  • addLoggerMBean will be impacted if it has been loaded.

    The following steps provide instructions on adding loggers using JConsole:

  1. Click Alfresco > Log4jHierarchy > Operations > addLoggerMBean.

  2. Type the full className in Name on the right hand pane.

  3. Click addLoggerMBean.

    A dialog box is displayed with the title Operation return value. If the operation is successful, the body of the dialog box contains the className you provided, preceded by log4j:logger=. If the operation is unsuccessful, the body of the dialog box shows null.

Error messages

Use this information to help troubleshoot your installation.


Error message on the console:

ERROR [AbstractImageMagickContentTransformer]
JMagickContentTransformer not available:
ERROR [AbstractImageMagickContentTransformer]
ImageMagickContentTransformer not available:
Failed to execute command: imconvert ...

These issues won’t cause the server to fail. Content Services is reporting that external document transformation engines are not available for use by the server. You can remove the transformation references if they’re not required.


Make sure the JAVA_HOME variable is set correctly for your Java installation.

FTP Socket

Error message on server startup:

ERROR [protocol] FTP Socket error

Port already in use Address already in use:
JVM_Bind at Method)

Check to see if you have any services running against port 8080 for the Content Services server or port 21 for the FTP integration.

Using the Node Browser

Use Node Browser in the Repo Admin Console or in Share Admin Tools as a debugging aid to browse the raw repository structure. This feature is intended for developers responsible for customizing the application.

This is a read-only feature with basic search capability.

  1. Open the Repo Admin Console.

  2. In the Support Tools section, click Node Browser. You see the Node Browser Console page.

  3. In the Store section, select the store of interest:

    • workspace://SpacesStore - live content
    • archive://SpacesStore - archived content (soft deleted)
    • workspace://version2Store - older content version history
    • user://alfrescoUserStore - nodes of type usr:user is stored, note that nodes of type cm:person is stored in the workspace://SpacesStore
    • system://system - info about installed modules
    • workspace://lightWeightVersionStore

    Each store is an area of the repository and within each store, the nodes of that store are organized hierarchically. The node displayed is the root node of the selected store.

  4. Click Root List.

    The Node Browser page displays details of the properties, aspects, children, parents, associations, source associations, and permissions for the selected node.

  5. Search the selected store, as needed:

    1. Select the search type: noderef, fts-alfresco, lucene, xpath, selectnodes, cmis-strict, cmis-alfresco, db-afts, db-cmis.

    2. Enter the search criteria in the field provided.

    3. Click Execute.

Using the Node Browser in Share Admin Tools

  1. Go to Share Admin Tools, and then click Node Browser.

    By default, the search criteria PATH:"/" is shown in the Node Browser field for the workspace://SpacesStore repository store. Each store is an area of the repository. The nodes contained within each store are organized hierarchically. The node displayed is the root node of the selected store.

    The default search type is set to fts-alfresco. For most administrative tasks, you can use the default search type.

    See Alfresco Full Text Search reference for more detail.

  2. Enter your search criteria in the Note Browser field.

  3. Click Search.

  4. Click the link in the Reference column to browse the details.

    The details of the properties, aspects, children, parents, associations, source associations, and permissions are displayed for the node.

  5. Click Back to Search to browse another node.

You can use another search syntax by choosing one of the following types from the Search list:

  • storeroot
  • noderef
  • xpath
  • fts-alfresco
  • cmis-strict
  • cmis-alfresco
  • db-afts
  • db-cmis

Debug an installation

When developing add-ins, fixing bugs, or changing Content Services from the source code, it is helpful to debug an instance running on a standard application server. You can configure Content Services and Eclipse to provide a real-time view of the server and to troubleshoot issues by stepping through the code line by line.

To debug a running server, you must connect to the JVM in which Content Services is running. The following steps configure the JVM to expose an interface for this connection, and then configure Eclipse to connect to and control that JVM.

Configure the JVM

You can configure the JVM to expose an interface for connection to the server.

Before you start, you must:

  • Have a fully installed, configured, and running instance of Content Services. These steps assume you’re using Tomcat on Windows, but the steps are similar for other application servers on other systems.
  • Have an IDE installed. These steps describe how to configure Eclipse, which must be installed first (Eclipse)
  • Download source code from This project has more instructions on how to set up a development environment.
  • Ensure the source code is the same version as the installed server.
  1. Verify that the server is not running.

  2. Edit the JVM options used to start the Tomcat instance.

    For example, set the following:

     JAVA_OPTS=%JAVA_OPTS% -server -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8082

    where address is a port for your system.

  3. Save the file and close the editor.

Configure Eclipse

This task describes how to configure Eclipse to connect to and control the JVM.

  1. From the Run menu, choose the Open Debug dialog.

  2. Right-click Remote Java Application and select New.

  3. In the Name box, type Debug Local Tomcat Alfresco.

  4. Next to Project, click Browse, and select Web Client. If this is not available as an option, ensure your source code matches that of your server.

  5. In Connection Properties, enter the port number.

  6. Check Allow Termination of remote VM if you want to be able to stop the server from the Eclipse console.

  7. Click Apply to save the configuration.

Troubleshoot an upgrade

Use these tips for diagnosing and resolving any issues that might arise as a result of an upgrade.

  1. Immediately after starting the server, make a copy of the alfresco.log file.

  2. In the alfresco.log file, note the locations of the temporary files containing the SQL statements executed during the upgrade, and make a copy of these temporary files.

  3. Submit the log file and temporary files to Alfresco Support.

Troubleshoot rules and actions

Use these troubleshooting tips when working with rules and actions.

Type specialization action problems with Mac OS/X**

If you’re using Mac OS/X 10.8.3 or later, the type specialization action is not performed when you save a Microsoft Word document.

To resolve this issue, edit your file to set the following value:


Troubleshoot clustering

Use these troubleshooting tips when testing cache clustering.

In Linux/Unix environments, you can use netstat -ln to check that the correct ports have been opened by the server on the correct network adapters. You can use telnet <hostname><port> to check if each open port can be reached by each cluster member.

If your cluster members are using NAT and IPv4 addresses, you might need to force the server to listen on IP V4 addresses rather than IP V6. To do this, add:

to the startup options of Content Services JVM. In a standard Linux/Unix installation, this would require editing of the JAVA_OPTS variable in the following script:


On a standard Windows installation, this would require adding the parameter just before ;-Dalfresco.home in:


and then running the scripts:

tomcat/scripts/serviceinstall.bat REMOVE
tomcat/scripts/serviceinstall.bat INSTALL

to re-register the service with the new option.

See Setting up clustering for more information on the process of initiating clustering and the options available for configuring clustering.

Troubleshoot LibreOffice subsystems

Use these tips for troubleshooting the LibreOffice subsystems.

  1. Enable the following log4j properties to debug:

    For information about how to create a file, see Key tools and files.

    Note: The OOoDirect debug entry is:

  2. If Tomcat is not shutdown gracefully, the soffice.bin process can’t be stopped. This can result in errors when starting Tomcat with port 8080 being is use. If this occurs, manually kill the soffice.bin process.

  3. You might see a failure to connect error message.

    If the LibreOffice process takes more than 10 seconds to fully start up, then Content Services fails to connect to it. If this occurs, manually kill the soffice.bin process before attempting to restart the Jodconverter subsystem.

    Note: The next time that you start LibreOffice, it usually starts fast enough to connect (this is due to operating system caching).

  4. If the LibreOffice home location is incorrect, the Jodconverter subsystem will still start, but no LibreOffice process will be running or connected. The error is reported in the console but not in the alfresco.log file.

    The correct value for the jodconverter.officeHome property varies with host operating system.

    • For Mac OS X, it should be set to the directory that contains MacOS/soffice.bin, which is /Applications/LibreOffice/Contents by default.
    • For other operating systems, it should be set to the directory that contains program/soffice.bin.
  5. When restarting the Jodconverter subsystem using JMX, you need to set the enabled property to true (this will also stop the JOD subsystem if it is running); then use the start operation to start the Jodconverter subsystem with the new property settings.

  6. The Jodconverter can run a pool of multiple reusable instances of the soffice LibreOffice process. To use this capability, set the jodconverter.portNumbers property to a comma-separated list of port numbers, all of which must be available for use. For example, 2022, 2023, 2024 for a pool of three soffice processes.

  7. The Jodconverter supports configurable restart behavior for the LibreOffice soffice process. To ensure that potential memory leaks in LibreOffice do not accumulate and affect performance, the JodConverter will restart an soffice process after a given number of tasks (transformations, metadata extractions) have been performed. The default for jodConverter.maxTasksPerProcess is 200.

  8. The Jodconverter allows long-running or hung tasks to be timed out. The first timeout is controlled by jodconverter.taskQueueTimeout, which is 30000 by default (30000 milliseconds = 30 seconds). If a task spends this long in a JodConverter queue awaiting execution, it’ll be dropped from the queue. The second timeout is controlled by jodconverter.taskExecutionTimeout, which is 120000 by default (120000 milliseconds = 2 minutes). If a task has been executing within an soffice process for longer than this period, that soffice process will be terminated and restarted.

  9. Throughput of OOo-related tasks, such as transformations, can be balanced against available hardware resources (memory, CPU) by altering the pool size and the two timeout timers.

Troubleshoot JMX Dumper

Use this information if you need to troubleshoot the JMX Dumper.

Invoking the JMX Dumper can result in a stack trace in the log file. When you open, it is trying to find a data source defined in the web.xml file. (<res-ref-name>jdbc/dataSource</res-ref-name>), but this data source is not declared in the alfresco.xml file.

To prevent this logging message for appearing, you can configure the data source in the $CATALINA_BASE/conf/[enginename]/[hostname]/alfresco.xml file.

Troubleshoot WebDAV

Diagnose and resolve issues that might arise when configuring WebDAV.

Content Services uses two implementations of WebDAV:

  • RFC-compliant WebDAV: alfresco/webdav
  • Microsoft-compliant WebDAV: alfresco/aos

Microsoft WebDAV extensions (MS-DAVEXT) are only partially compatible with the WebDAV standard, therefore it is recommended that you use /alfresco/aos on Windows clients and /alfresco/webdav on Linux-based systems.

Unable to mount WebDAV share (Windows)

  • Check if Content Services has finished loading. Look for a Server startup message in the log file
  • Check if the connection works if you use the IP address instead of the host name
  • Check if you can browse folders using https://<alfresco_ip>/alfresco/aos in a web browser
  • Add your server IP to the Trusted sites list in Windows Internet Explorer
  • Make sure the WebClient service is running. To do so, follow the steps:

    1. Start services.msc.
    2. Start the WebClient service.

    Note: For details on running the WebClient service, see Enabling the WebClient service in Windows.

  • If you’re not using SSL, check your connection configuration for Windows and Microsoft Office.

    Note: Refer to Microsoft for details on setting the Basic Authentication Level key in the Registry Editor.

  • If you can connect to the server but can’t authenticate your login details, check if you can use the same user name and password to log in to Alfresco Share.

Move file or folder using WebDAV on an Ubuntu client causes loss of metadata and creates a new node reference

There is a known issue where Ubuntu creates a new nodeRef when you move a file or a folder in WebDAV, because it uses PUT and DELETE methods instead of a MOVE method. As a result, the nodeRef for the file or folder changes and any associated metadata is lost. This issue applies to all versions of Ubuntu, but does not occur when using a Windows client.

Editor role can’t edit content using WebDAV and Cyberduck version 4.4+

There is a known issue when using WebDAV with Cyberduck 4.4 and later, where content can’t be edited due to insufficient permissions. To avoid this, you can either use a version of Cyberduck earlier than 4.4, or assign permissions to the user to allow them to create files.

Slow response when working with WebDav resources on Microsoft Windows Vista or 7

There is a known issue where you may experience poor performance when opening a WebDav folder, copying files to or from a WebDav folder, or changing from one folder to another on the WebDav folder. This can be caused because when WebClient issues a WebDAV command it checks for a web proxy server. If you have Auto-Proxy detection enabled and there isn’t a proxy server in the environment between the client and WebDAV resource, WebClient waits for the timeout of Auto-Proxy detection. Command completion therefore will take longer due to the wait for the Auto-Proxy detection timeout.

OpenLDAP tips

Use these tips when working with OpenLDAP.

There are a number of things to note:

  • The maximum number of results returned has been increased from the default of 500 that even applies to paged results. See the OpenLDAP documentation on limits. If you have more than 500 users or groups this would be an issue.
  • Digest authentication has been configured to map from a user ID to the corresponding distinguished name. See the example data.
  • Passwords are in clear text (so that any authentication mechanism can be used). It is possible they can be in the correct hashed form for the MD5 digest to work.
See slapd.conf(5) for details on configuration options.
# This file should NOT be world readable.
include  /usr/local/etc/openldap/schema/core.schema
include  /usr/local/etc/openldap/schema/cosine.schema
include  /usr/local/etc/openldap/schema/inetorgperson.schema

# Define global ACLs to disable default read access.

# Do not enable referrals until AFTER you have a working directory
# service AND an understanding of referrals.
#referral  ldap://

pidfile   /usr/local/var/run/
argsfile   /usr/local/var/run/slapd.args

# Load dynamic backend modules:
# modulepath /usr/local/libexec/openldap
# moduleload
# moduleload
# moduleload
# moduleload
# moduleload

# Sample security restrictions
# Require integrity protection (prevent hijacking)
# Require 112-bit (3DES or better) encryption for updates
# Require 63-bit encryption for simple bind
# security ssf=1 update_ssf=112 simple_bind=64

# Sample access control policy:
# Root DSE: allow anyone to read it
# Subschema (sub)entry DSE: allow anyone to read it
# Other DSEs:
#  Allow self write access
#  Allow authenticated users read access
#  Allow anonymous users to authenticate
# Directives needed to implement policy:
# access to dn.base="" by * read
# access to dn.base="cn=Subschema" by * read
# access to *
# by self write
# by users read
# by anonymous auth
# if no access controls are present, the default policy
# allows anyone and everyone to read anything but restricts
# updates to rootdn. (e.g., "access to * by * read")
# rootdn can always read and write EVERYTHING!

# BDB database definitions

database  bdb
suffix  "dc=company,dc=com"
rootdn  "cn=Manager,dc=company,dc=com"
# Cleartext passwords, especially for the rootdn, should
# be avoid. See slappasswd(8) and slapd.conf(5) for details.
# Use of strong authentication encouraged.
# This is secret ....
rootpw          {SSHA}u9AUUYOSVX6idlXcwyYOAG6G84oHFpvG
# The database directory MUST exist prior to running slapd AND
# should only be accessible by the slapd and slap tools.
# Mode 700 recommended.
directory  /usr/local/var/openldap-data
# Indices to maintain
index  objectClass  eq

# Clear text to allow hashing
password-hash  {CLEARTEXT}

# SASL mappings for md5 digest authentication
# Extract the user id and use as the search key



# Tweaks to increase the result set size and max query time

sizelimit 50000
timelimit 3600

The following is a very simple example LDIF file that defines People and Groups Organizational units and some example users and groups.

# Initial directory contents
dn: dc=company,dc=com
dc: company
objectClass: top
objectClass: domain

dn: ou=People,dc=company,dc=com
ou: People
objectClass: top
objectClass: organizationalUnit

dn: ou=Groups,dc=company,dc=com
ou: Groups
objectClass: top
objectClass: organizationalUnit

dn: uid=fullname,ou=People,dc=company,dc=com
objectclass: inetOrgPerson
sn: Name
cn: Full Name
userPassword: inClearText
telephoneNumber: 1234567890
uid: fullname
givenName: Full
o: Company Software Inc.

dn: uid=walrus,ou=People,dc=company,dc=com
objectclass: inetOrgPerson
sn: Rus
cn: Wal Rus
userPassword: inClearText
telephoneNumber: 1234567890
uid: walrus
givenName: Wal
o: Company Software Inc.

dn: cn=Group One,ou=Groups,dc=company,dc=com
objectclass: groupOfNames
cn: Group One
member: uid=fullname,ou=People,dc=company,dc=com

dn: cn=Group Two,ou=Groups,dc=company,dc=com
objectclass: groupOfNames
cn: Group Two
member: cn=Group One,ou=Groups,dc=company,dc=com
member: uid=walrus,ou=People,dc=company,dc=com

Active Directory tips

Tips for using Active Directory with the LDAP synchronization.

  • You might need to give special permissions in the Active Directory to the account that you’re using to do the LDAP bind (as configured in To do this, open Active Directory Users and Computers, right click on the domain, and select Delegate Control… Click Next, then select the user that you’re using for the LDAP bind and click Next. The permission that they will need is on the next screen Read all inetOrgPerson information.
  • The example URL in does not use SSL. SSL is recommended for production systems. You’ll need to switch the port from 389 (below, non-SSL) to 636 for SSL.
  • It is often helpful to screen out non-user accounts and disabled accounts. The default user queries in the ldap-ad subsystem type do this by checking bit fields on the userAccountControl attribute. For example:


Troubleshoot SMTP inbound email using StartTLS

For StartTLS support to work for inbound email, you must configure SSL for Java.

To identify whether you’re having this problem, enable DEBUG logging for the class org.subethamail in your file.

startTLS() failed: no cipher suites in common

Also, to enable efficient inbound mail server logging in debug mode, you need a log4j option that allows you to track mails, including the sender details, recipient details, subject and the reason for rejection/acceptance. To do so, enable DEBUG logging for the class org.subethamail.smtp.server.ConnectionHandler as shown:  

The following process outlines one method for creating a self-signed certificate. However, this can differ between JVM vendors, so see the JVM documentation for more information.

  1. Create a suitable key and certificate:

     keytool -genkey -keystore mySrvKeystore -keyalg RSA
  2. Add the following somewhere in your Tomcat configuration. For example, /etc/tomcat5/tomcat7.conf.


Handle higher rate of outbound TCP connections

If you’re using the Web Services API on a Windows client and frequently see errors such as Address already in use: connect in the client application, you might need to tune the client operating system parameters so that it can handle a higher rate of outbound TCP connections.

  1. Open the Registry.

  2. Under the following registry entry:

  3. Key in the registry of the Windows client machine.

  4. Add the following registry entries:

    • TcpTimedWaitDelay

      Add this DWORD with a value of 30.

    • MaxUserPort

      Add this DWORD with a value of 32768.

  5. Refer to the Windows documentation for further details on these registry entries.

Troubleshoot IMAP

Use this information to troubleshoot IMAP problems.

IMAP scale limitations

If you mount more than 5000 folders or mailbox folders, depending on the IMAP client that you’re using, you might not be able to view more than the first 5000 folders.

In order to avoid this situation, you should limit the number of folders that are being mounted.

For example:

  • Do not mount from the company root space if you know that you have a very large folder structure. Choose a specific site to reduce the number of folders being mounted.
  • Do not extract attachments to a separate folder (imap.attachments.mode=SEPARATE), particularly for large repositories. When you specify imap.attachments.mode, choose one of the following settings:
    • imap.attachments.mode=COMMON: all attachments for all emails are extracted to one folder
    • imap.attachments.mode=SAME: attachments are extracted to the same folder as the original message

IMAP server error message

Exception in thread "Thread-53" java.lang.RuntimeException: Cannot assign requested address:
JVM_Bind at
Caused by:
Cannot assign requested address: JVM_Bind

This error message is related to the IP address or hostname that has been provided for binding. To resolve this issue:

  • Check that the IP address or hostname you provided is correct for your setting.
  • Check that the port you’re using is not blocked. The default port to use is 143.
  • Check that firewalls are not blocking this IP address or hostname.
  • Use the command line tool Netstat to check your network connections.

    Note: You should not use localhost as the - update this value with the IP address (or corresponding DNS address) of your external IP interface. A value of in Unix will make it listen on the specified port on all IP interfaces.

Troubleshoot database scheme problems

The Schema Difference Tool provides a way of identifying and troubleshooting problems in database schemas. Such problems can sometimes arise when performing certain version upgrades or customized installations.

The Schema Difference Tool can be used when troubleshooting or examining the database schema for a repository. The tool has two main functions:

  1. Producing schema dumps as XML files.
  2. Validating a database schema.

Schema dumps were available in previous versions of Content Services. However, prior to the introduction of the Schema Difference Tool, the only way to judge the validity of the schema was to examine the file manually and compare schemas with simple text tools such as the Unix diff command. The Schema Difference Tool performs a certain amount of automatic comparison that removes much of the effort needed in making these comparisons.

If any changes are made to the database schema during server start-up (such as a fresh install) then the tool performs both schema dumping and validation as described. The dumps and validation are made both pre-upgrade (that is before the schema changes) and post-upgrade.

Definition of terms used

The terms given are used throughout the rest of this section.

  • Database object

    A schema, sequence, table, column, index, primary key or foreign key.

  • Reference schema

    The definitive representation of a repository schema for a given schema version on a vendor specific RDBMS. The reference schema is a model for what should be present in the database after installing or upgrading a repository to a particular version. A reference schema is presented in the same XML format as a schema dump. For example, a schema reference can be produced for MySQL on version 5025 of the repository schema.

  • Target schema

    The database schema that will be compared and validated with respect to a reference schema. For example, if installing an repository from scratch, then the newly created schema will be a target schema for comparison against the appropriate reference schema.

Perform schema dumps

Schema dumps are XML representations of the database schema.

Schema dumps can take place in two situations:

  1. The dump is triggered automatically on startup due to a difference being found between the reference and actual database schema.
  2. The dump is manually triggered by using a JMX client.

Each of these scenarios is described in the following sections.

Automatic dumps

Schema dumps are performed automatically on server startup, if changes in database schema are detected.

Schema dumps are XML representations of the RDBMS schema. They should conform to the XSD: The XSD file is embedded in the repository.

A schema dump is performed automatically during repository server start up, if there were changes made to the database schema. The log will indicate if any dumps were performed, and entries such as these will be present:

2017-02-16 11:51:19,907 INFO  [org.alfresco.repo.domain.schema.SchemaBootstrap] [localhost-startStop-1] Normalized schema dumped to file
2017-02-16 11:51:19,907 INFO  [org.alfresco.repo.domain.schema.SchemaBootstrap] [localhost-startStop-1] Normalized schema dumped to file

Similar entries for the post-upgrade files will also be present.

Note: The legacy tool is still included and will create dumps of its own - the log messages look similar but should not be confused with the new format dumps.

Note: JBPM has been removed from Content Services. Schema dump will ignore any JBPM tables and not treat their presence or absence as an error.

Trigger dumps by using JMX

Schema dumps can also be triggered manually by using a JMX client.

In addition to automatic dumping, dumps can be manually invoked by use of the JMX interface.

The JMX category Alfresco > DatabaseInformation > SchemaExport contains two operations:

  1. java.util.List dumpSchemaToXML()
  2. java.util.List dumpSchemaToXML(String prefixList)

The first operation takes no parameters and when invoked will create three dump files one for each prefix alf_ and act_. The prefix means that only tables and sequences whose names begin with the prefix will be included in the dump. Related items, such as the indexes belonging to a particular table, will be dumped regardless of name.

The second variation takes a single String parameter and is a comma-separated list of prefixes that you wish to dump. If this operation were invoked with the parameter alf_acl_, alf_node_ for example, then two files would be created (one for each prefix). The tables dumped in the first file would include alf_acl_change_set and alf_acl_member. Tables in the second file would include alf_node_aspects and alf_node_assoc. Neither file would include alf_locale or alf_permission since they do not carry one of the supplied prefixes.

Both of these calls will result in the log showing the location of the dumped files, but they also return a List of path names. JConsole will helpfully display these lists in a copy/paste friendly manner.

Perform schema validation

Schema validation of schema dumps can happen either due to a schema change during repository start up, or can be triggered manually by using JMX.

Schema validation is performed with differencing and validation.


Differencing produces similar information to that obtained by using the Unix tool diff against a known ‘good’ reference schema dump and a potentially problematic target schema dump.

However, since the tool is designed for performing a comparison between two database schemas, rather than arbitrary text, the output is more specific about the types of difference.

The types of difference that can be reported are:

  • A database object appears in both the reference and target schemas, but has differences in its properties. For example if an index appears in both schemas but has a different name.
  • A database object appears in the reference schema but no corresponding object has been identified in the target database.
  • A database object appears in the target schema but no corresponding object has been identified in the reference database.

One advantage of the Schema Differencing Tool differencing over traditional diff tool comparisons is that an index is not recognized by the exact text appearing in a dump. Instead it is identified by which table the index belongs to, which columns are indexed and in what order. If an index has the expected name and belongs to the correct table but has the wrong columns, or the correct columns in the wrong order, then differences will be reported. Or conversely, if the correct table has an index with the correct columns in the correct order, but has the wrong index name, then this will be reported. The name can be ignored during comparisons (useful for auto-generated index names) or can be taken into account. Part of the task of producing reference schema files is to specify this behavior using DbValidator objects, which are explained in the following sections.

For example, suppose we have the following index defined in the reference schema:

Index name permission_id
Parent table alf_access_control_entry
Columns permission_id, authority_id, allowed, applies

This index is specified in the schema reference file in this way (parts omitted for brevity):

<table name="alf_access_control_entry">
  <!-- column definitions, primary keys and foreign keys ommitted -->
    <index name="permission_id" unique="true">
    <!-- further index definitions ommitted -->

When the target schema’s index is compared against this reference then firstly a list of candidate matches are produced. There can be more than one matching index in the target schema, in which case a redundant database object warning is issued.

Candidate matches are produced dependent on object type.

For indexes:

  1. If the parent table is the same and the index name is the same, then it is considered the same index.
  2. If the name is different but the parent table is the same and the columns indexed are the same, and in the same order, then it is is considered to be the same index.

Taking the first scenario for matching and using the permission_id index defined in the example, then if the permission_id index in the target database has the allowed and applies columns in the reverse order than is expected, the log file would notify us of validation problems:

2012-01-31 11:24:24,280  WARN  [domain.schema.SchemaBootstrap] [RMI TCP Connection(11)-]
Schema validation found 2 potential problems, results written to:

The contents of the report file would look similar to the following:

Difference: expected index .alf_access_control_entry.permission_id.columnNames[2]="allowed",
but was .alf_access_control_entry.permission_id.columnNames[2]="applies"
Difference: expected index .alf_access_control_entry.permission_id.columnNames[3]="applies",
but was .alf_access_control_entry.permission_id.columnNames[3]="allowed"

Each line shows a problem with a particular database property. Here it indicates that the property at the path .alf_access_control_entry.permission_id.columnNames[2] has the value applies but according to the reference schema should be allowed. The leading dot of the path can be ignored (the schema name would be present before the leading dot in the case of Oracle for example), then there is the table name alf_access_control_entry, the index name permission_id within that, and a zero-indexed list property within that. The third item (index 2) is the property at fault: columnNames[2].

Similarly, the next line indicates that the next item in the column name list, columnNames[3], has the value allowed but was expected to be applies.


The Schema Difference tool can use schema reference XML files to perform validation in addition to that performed by simple differencing.

Validation allows the application of more complex rules than whether there is a difference between two property values. Validation is performed by DbValidator objects. A chain of DbValidator objects is associated with each database object in the reference schema. Each of these is executed in turn and given the chance to create validation errors based on the corresponding object in the target schema.

If an index has not been given a specific name then the RDBMS will auto-generate one at creation time. This means thatthe reference schema can’t specify the exact name that the index in the target database will have. This would lead to schema differences being reported if it were not for the use of validators.

A NameValidator can be specified for such an index:

<index name="SQL120116153558430" unique="true">
    <validator class="org.alfresco.util.schemacomp.validator.NameValidator">
        <property name="pattern">SQL[0-9]+</property>

This example is from a schema reference file (Schema-Reference-ALF.xml) and indicates that although in the original reference schema the index was named SQL120116153558430 any index having the appropriate parent table, column names (and column order) is valid as long as the name matches the regular expression SQL[0-9]+.

When the validator is invoked, it checks that the name property of the index matches the supplied regular expression. In addition to this, the validator reports, when configured to, that it takes responsibility for the name property of the index. This stops the Schema Difference Tool from applying the differencing logic to the property. A DbValidator can choose to apply its validation in addition to the differencing logic by not taking sole responsibility for any properties. Conversely a validator can also take sole responsibility for an entire database object in which case no differencing logic is applied to any part of the object.

Perhaps a specific unsupported upgrade path has introduced an unexpected schema change - it might not be a problem, but it is important that differences are highlighted so that a decision can be made on whether the difference represents a problem and whether a fix will need to be made. On running the Schema Difference Tool, the following might be observed in the log files:

2012-01-31 14:28:50,697  WARN  [domain.schema.SchemaBootstrap] [main] Schema validation found 1 potential problems, results written to:
2012-01-31 14:28:54,682  INFO  [domain.schema.SchemaBootstrap] [main] Compared database schema with reference schema (all OK):
class path resource [alfresco/dbscripts/create/org.hibernate.dialect.Oracle9Dialect/Schema-Reference-ACT.xml]

The ACT database object is as expected, but there is a difference between the target schema and the ALF (alf_ prefixed database objects) schema reference. Looking at that file it can be seen that an index that is expected to have been auto-generated has been created with an explicit name:

Validation: index"idx_alf_ace_auth" fails to match rule: name must match pattern 'SQL[0-9]+'

Specifically, the error report is stating that the index defined in the schema reference having the name SQL120131142718040 belonging to the table ALF_ACCESS_CONTROL_ENTRY is expected to be named in the same way: prefixed with SQL then a string of one or more digits.

A similar problem to the auto-generated name problem is when a database object is created automatically. Some databases create indexes on the fly, rather than being an explicit part of the schema declaration. It is not known whether they will exist at the time the Schema Difference Tool is run. To suppress such errors an IgnoreObjectValidator can be used - it takes responsibility for validation of the associated database object, but performs no actual validation

In addition to automatic validation, validation can be manually invoked by use of the JMX interface.

Note: This is an enterprise only feature.

The JMX category Alfresco > DatabaseInformation > SchemaValidator contains one operation:

void validateSchema()

The operation takes no parameters and returns nothing. However, if the operation is invoked then validation will be performed and the log will show the results:

2012-01-31 14:51:46,770  INFO  [domain.schema.SchemaBootstrap] [RMI TCP Connection(13)-] Compared database schema
with reference schema (all OK): class path resource
2012-01-31 14:51:50,910  INFO  [domain.schema.SchemaBootstrap] [RMI TCP Connection(13)-] Compared database schema
with reference schema (all OK): class path resource

In the example there were no problems found in the target schema.

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