Changes in Virtual DataPort 6.0¶
Changes introduced in Virtual DataPort 6.0:
- Changes in VQL Syntax
- Changes in VQL Statements
- Dependencies to Develop Custom Elements (Functions, Wrappers…)
- Importing Roles from an LDAP Server
- JDBC Data Sources
- JDBC Driver
- Memory Usage Options
- ODBC Driver
- REST Web Services No Longer Return the HTTP Code 204 by Default
- Stored Procedures
- User Privileges
- Version Control System Integration (VCS)
- Windows Services
- Features Deprecated in Denodo 6.0
- Features Removed in Denodo 6.0
Denodo 6.0 introduces changes to the VQL syntax to avoid ambiguities in the process of parsing VQL statements.
Because of this, you may have to review the queries sent by third-party clients to Virtual DataPort.
Starting with Denodo 6.0, consider the following:
It is mandatory to surround the values of the right side of a condition with a multi-valued operator. These operators are:
textual similarity (
SELECT * FROM V1 WHERE field_1 IN (1, 2)
In earlier versions, the parentheses are optional.
It is mandatory to separate with the clause
ANDthe values of the operator
field_1 BETWEEN value_1 AND value_2.
In earlier versions, you can execute
field_1 between value1, value2.
It is mandatory to surround literals with single quotes as indicated by the SQL standard. In earlier versions, you could use either single or double quotes for this, but not anymore.
In Denodo 6.0, the double quotes are used to surround identifiers with special characters.
Surround “Unicode” identifiers with double quotes. In Denodo 5.5, you could only do it with French quotes. In Denodo 6.0 you can use French quotes as well, but they may be deprecated in the future.
For example, the following two statements are equivalent:
CREATE VIEW `view with spaces in the name` ...
CREATE VIEW "view with spaces in the name" ...
To provide the value of an interpolation variable, do it with the “=” operator. E.g. the following query is no longer valid.
SELECT * FROM view1 WHERE input_status > 'value'
In previous versions, you could use any operator and the result was the same as using
=. However, it was semantically incorrect.
In literals, you can no longer use the backslash (
\) to escape the simple quote (
'). To escape a single quote, you have prefix it with another single quote.
For example, in Denodo 5.5, the following query returns he'llo and in Denodo 6.0, returns he.
SELECT 'he\'llo' AS f1
In Denodo 6.0, the following properties of the “Source Configuration” of JDBC and ODBC data sources have been removed:
- “ORDER BY collation” (
ORDERBYCOLLATIONparameter of the
SOURCECONFIGURATIONclause in the
- “Delegate ORDER BY Collation” (
DELEGATEORDERBYCOLLATIONparameter of the
SOURCECONFIGURATIONclause in the
When you import a data source that has these properties set, their value is ignored.
Removing these properties does not cause a loss of functionality. They were removed because having these properties configured in a data source could cause merge joins to produce invalid results. The reason is that the database could return the results sorted with a non-binary collation, while the merge join expects the result sets sorted with a binary collation. Instead, the properties “Supports binary ORDER BY collation”, “Delegate ORDER BY collation modifier” and “Delegate binary ORDER BY collation” control correctly how Virtual DataPort pushes down the ORDER BY clause to databases.
The section ORDER BY Properties of the Source Configuration of the Virtual DataPort Administration Guide explains the meaning of these new properties. However, it is very rare that you need to modify their default value.
Some of the jars required to develop custom elements (custom functions, custom wrappers, stored procedures and custom input filters) now have different name.
However, the names of the Java packages and classes has not changed. Therefore, the custom elements developed for previous version will work correctly in Denodo 6.0.
The new names are documented in the Virtual DataPort Developer Guide.
In Denodo 6.0, in the “Import roles from LDAP” dialog of “Roles Management”, the value you have to enter in “Role base” is different from the previous versions.
To import the roles, Virtual DataPort queries the LDAP server and this LDAP query is performed under a specific level.
In Denodo 5.5 and earlier versions, this level is the concatenation of two values:
- The base search of the URI of the LDAP data source.
- And, the value of the “Role base” field of the settings of the database.
In Denodo 6.0, this level is just the value of the “Role base” field.
For example, if the URL of the LDAP data source used by the database is “ldap://acme.denodo.com:389/DC=Denodo” and “Role base” on the database is
- In Denodo 5.5 and earlier, the search is performed under the level
- In Denodo 6.0 and 7.0, the search is performed under the level
Starting with Denodo 6.0, the property “Supports binary ORDER BY collation” of the JDBC data sources is “yes” by default, when the database adapter is Teradata. In previous versions, the default value was “no”.
Setting this property to “yes” allows delegating merge joins to Teradata, which is the fastest join method. However, is very important that in Teradata, the default collation is set to binary. Otherwise, the results of the merge joins executed by Virtual DataPort (not delegated to the database) may be incorrect.
If you cannot set the default collation to binary, set this property to “no” in all the data sources that connect to a Teradata database.
Starting with Denodo 6.0, the base views created from query using the administration tool have the option “Delegate SQL Sentence as subquery” set to “yes”.
When this option is enabled, at runtime, Virtual DataPort delegates the
SQL query of the base view as a subquery in the
FROM clause. This
increases the number of operations that are delegated to the database.
However, some queries may fail if the syntax of the delegated query is
not accepted by the database.
The section View Configuration Properties of the Virtual DataPort Administration Guide explains in more detail how this property works and its limitations.
Starting with Denodo 6.0, the Denodo JDBC driver is located at the
Starting with Denodo 6.0, the method
DatabaseMetadata.getMaxColumnNameLength() of the Denodo JDBC driver
returns the maximum number of characters Virtual DataPort allows for a
In earlier versions, this method always returns
0, which means that
the limit is unknown. Some JDBC clients such as “JasperReports” do not
work well with this value.
Starting with Denodo 6.0, the Denodo JDBC driver is compiled with Java 7.
The applications that use this driver and that run with earlier versions of Java will have to update their version of Java. Otherwise, the applications will not be able to load this driver.
The JDBC driver of earlier versions of Denodo cannot connect to Denodo 6.0
Starting with Denodo 6.0, the operation
the JMX MBean
VDBServerManagementInfo returns the complete list of
requests sent to the server. In earlier versions, this operation only
returns information about
With this change, you also can monitor Data Definition Language and
Starting with Denodo 6.0, by default, Virtual DataPort limits the total amount of memory used by a query.
This feature existed in earlier versions of Denodo, but it was disabled by default.
The section Limit the Maximum Amount of Memory of a Query describes of the Virtual DataPort Administration Guide this option.
Starting with version 6.0, the Denodo Platform provides its own ODBC
driver, which is based on the PostgreSQL ODBC driver. Whenever is
possible, stop using the PostgreSQL one and begin using the Denodo ODBC
driver. It is located at
The steps to configure it on Linux are slightly different. They are documented in the Virtual DataPort Developer Guide.
The Denodo ODBC driver performs better than the PostgreSQL ODBC driver because it has several changes tailored specifically to the Denodo Platform.
Starting with Denodo 6.0, the ODBC interface returns date fields with millisecond precision. In previous versions, this interface returns the dates with second precision.
This change only applies to the ODBC interface. The JDBC interface returns dates with millisecond precision in this version and the previous ones.
Starting with Denodo 6.0, the REST Web services published by Denodo no longer return the HTTP code 204 (No content) by default.
In previous versions, the RESTful web service and the published REST web services return the HTTP code 204 in the following scenarios:
- The request has the parameter
$filterand does not return any rows.
- Or the request queries a view that does not return any rows.
This applies only to the JSON and XML representations; not to the HTML one.
If you want the REST Web services to go back to the behavior of previous versions (returning 204), execute the following command from the VQL Shell of the Administration Tool:
SET 'com.denodo.wsgenerator.restws.noResultsReturnHTTPCode' = '204';
After executing this statement, all the REST Web services that you deploy or redeploy will:
- Return the HTTP code 204 instead of 200 when the result does not return any rows.
- They will return an empty response, instead of an empty XML or JSON document (depending on the representation requested).
You do not need to restart Virtual DataPort to apply this change, but you have to redeploy the REST web services.
REST services continue returning the HTTP code 204 when updating (HTTP PUT request) or deleting rows (HTTP DELETE request).
The behavior of the RESTful Web service (http://localhost:9090/denodo-restfulws) has changed in the same way. To configure it to return the HTTP code 204 instead of 200 in the scenarios listed above, follow these steps:
- Edit the file
other_settings.xmlof the directory
- Set the value of the property
- Restart the Virtual DataPort server to apply the changes.
The return parameter
old type of the
stored procedure has been renamed to
Starting with Denodo 6.0, users can query views that belong to databases other than the one they are connected. Therefore, even if a user is not allowed to connect to a database, she can query the views of that database over which she has read access, when she is connected to another database. However, as it cannot connect to that database, it will not be able to create, edit or drop its views.
In previous versions, the users can only query views that belong to databases over which they have the privilege “Connect”.
The process of importing checking out a database from a Version Control System (VCS) has changed in this version.
In Denodo 5.5, when a statement obtained from the VCS fails, the process is stopped and nothing is imported.
In Denodo 6.0, when a statement obtained from the VCS fails, the Server continues executing the next one. This is necessary so is possible to partially update a database that has elements that depend on elements from another database that does not exist yet.
Starting with Denodo 6.0, when you change the user that starts the Denodo Windows services, you do not have to modify the value of the parameter “jna_tmpdir”. In Denodo 6.0, this property points to a folder in the Denodo installation.
In previous versions, this parameter points to the TEMP directory of the user that installed the Denodo Platform. Therefore, when you change the user that runs the Denodo Windows services, in previous versions you have to change the value of the “jna_tmpdir”. But you do not have to do this in Denodo 6.0.
This section lists the features that are marked as deprecated in Denodo 6.0. Deprecated features are not actively maintained and may be removed in future versions of the Denodo Platform. We recommend not using them anymore.
ALTER TABLE <base view name>
ADD SEARCHMETHOD is
When creating a base view, define the search methods in the
CREATE TABLE statement instead of executing a
CREATE TABLE and
then, adding the search methods with the statement
This reduces the number of statements Virtual DataPort has to process.
For example, instead of running this:
CREATE TABLE internet_inc I18N us_est ( iinc_id:long, summary:text, ... ... ); ALTER TABLE internet_inc CACHE OFF TIMETOLIVEINCACHE DEFAULT ADD SEARCHMETHOD internet_inc( I18N us_est CONSTRAINTS ( ADD iinc_id (any) OPT ANY ADD summary (any) OPT ANY ... ... ) OUTPUTLIST (iinc_id, specific_field1, specific_field2, summary, taxid, ttime ) WRAPPER (jdbc internet_inc) );
Run the following (i.e. just one command)
CREATE TABLE internet_inc I18N us_est ( iinc_id:long, summary:text, ... ... ) CACHE OFF TIMETOLIVEINCACHE DEFAULT ADD SEARCHMETHOD internet_inc( I18N us_est CONSTRAINTS ( ADD iinc_id (any) OPT ANY ADD summary (any) OPT ANY ... ... ) OUTPUTLIST (iinc_id, specific_field1, specific_field2, summary, taxid, ttime ) WRAPPER (jdbc internet_inc) );
The Denodo JDBC driver is capable of creating its own pool of connections to Virtual DataPort. This feature is deprecated.
This pool of connections is configured with the parameters
maxIdle, which will
no longer be valid when this feature is removed.
These following authentication methods of published web services have been deprecated:
- For REST web services, “HTTP Basic with LDAP” and “WSS Basic with LDAP”.
- For SOAP web services, “HTTP Basic with LDAP”.
SQLFRAGMENT clause of the
CREATE WRAPPER JDBC statement has
getNumOfAffectedRows() of the stored procedures API has
been deprecated. Do not override this method in new stored procedures.
Although it is deprecated, the method will probably not be removed from future versions of the API in order to maintain binary compatibility with old stored procedures.
The following methods of the custom wrappers API have been deprecated:
The XMLA adapters for SAP (i.e. “SAP BW 3.x (XMLA)” and “SAP BI 7.x (XMLA)”) have been deprecated. We suggest you begin using the adapter “SAP BI 7.x (BAPI)”.
This section lists the features that are no longer available in Denodo 6.0.
money have been removed.
If you used the type
The generic SOAP Web Service interface has been removed. In earlier versions, this interface is deployed at http://localhost:9090/denodo-vdp-wsclient/services.
This change does not affect SOAP Web services that publish one or more views. They are still fully supported.
As an alternative to clients that cannot use the JDBC driver, Denodo provides the RESTful Web service (http://localhost:9090/denodo-restfulws) and the ODBC interface.