Known issues and limitations for Data Virtualization

General issues

Unlocking a Data Virtualization connection incorrectly requires an access token after specifying to use your platform login credentials

Applies to: 5.3.0 and later

When you use a Data Virtualization connection in catalogs or projects, you might be prompted to unlock the connection with your own personal credentials. If you select Use my platform login credentials, the Access token input field is incorrectly marked as required, and you are unable to connect.

Workaround: Open the Data Virtualization connection asset explicitly in the current catalog or project (Platform connections) and then select Use my platform login credentials. You will not be prompted to provide an Access token. Save the changes.

Running the NUMTABSREMOTE view for multiple catalog sources returns -1 as the total number of tables

Applies to: 5.3.0 and later

When you run the NUMTABSREMOTE view to retrieve the total number of tables for multiple catalog sources, the output returns -1 and this is expected. The console displays xxx/? with xxx as the placeholder for the number of tables in the selected catalog. For example: 123/?.

Audit issues

CHECKING audit category might generate duplicate entries

Applies to: 5.3.1

If a user runs a statement through a JDBC or ODBC connection on a table for which they do not have access privileges, the CHECKING audit category might generate duplicate entries.

Note: This issue occurs only for statements executed through JDBC/ODBC connections. Statements that are ran using the Db2 CLI work as expected and do not produce duplicate entries.

Audit functionality might not be updated after you upgrade to Data Virtualization version 5.3.1

Applies to: 5.3.1

After you upgrade Data Virtualization to IBM Software Hub version 5.3.1, the audit functionality might not be updated.

Symptoms:

1. The /mnt/blumeta0/support/audit_installation.log log file in the Data Virtualization head pod c-db2u-dv-db2u-0 contains the following message: SQL1024N A database connection does not exist. Also, if you successfully upgraded to IBM Software Hub version 5.3.1 from version prior to 5.3.0, the required table AUDIT.CONFIG does not exist. You can check for the existence of the table by running SELECT * FROM AUDIT.CONFIG.
2. When you enable the auditing of SQL statements by using the DVSYS.TOGGLEAUDITLOGGING_STMTS procedure, this error displays: SQL0438N Application raised error or warning with diagnostic text: "Procedure not initialized by installaudit". SQLSTATE=75000.

Workaround: As a Data Virtualization Administrator, use the DVSYS.TOGGLEDEFAULTAUDITLOGGINGCOMPLETE procedure to uninstall and reinstall the Db2 audit facility. See also Enabling and disabling the Db2 audit facility in Data Virtualization.

Note: This workaround resets all the changes made to the default Data Virtualization audit policy named DV_AUDIT_DEFAULT.

1. Uninstall the audit facility by running this procedure:

   CALL DVSYS.TOGGLEDEFAULTAUDITLOGGINGCOMPLETE('OFF')

2. Then reinstall the audit facility by running this procedure:

   CALL DVSYS.TOGGLEDEFAULTAUDITLOGGINGCOMPLETE('ON')

Incomplete audit logging when stopping Big SQL or upon Db2 termination

Applies to: 5.3.0 and later

If you run the bigsql stop command, or in the case of an abrupt unhandled Db2 termination (crash), any statements or events that are in buffer but had not been written to disk yet are not captured in the audit logs. Buffer size can be configured by using the audit_buf_sz configuration parameter.

Audit runs generate an ignorable error entry

Applies to: 5.3.0 and later

Every audit run generates an additional (false) error entry in the diagnostic logs, indicating a path access permission issue. You can safely ignore this error.

Example of an error that you can ignore:

2025-11-13-13.18.07.454178+000 E6480E972             LEVEL: Error (OS)
PID     : 2109615              TID : 140412667792896 PROC : db2fmp (
INSTANCE: db2inst1             NODE : 000            DB   : BIGSQL
APPID   : *N0.DB2.251030051340
HOSTNAME: c-db2u-dv-db2u-0
FUNCTION: DB2 UDB, oper system services, sqloQualifyPath, probe:20
MESSAGE : ZRC=0x870F0152=-2029059758=SQLO_RC_NOT_SET
          "A return code from a function that conditionally does not set one has been inappropriately consumed."
CALLED  : OS, -, realpath                         OSERR: EACCES (13)
DATA #1 : Codepath, 8 bytes
0
DATA #2 : signed integer, 4 bytes
2
DATA #3 : String, 53 bytes
/mnt/logs/audit/temp_del_path/stmt_20251113131807.del
DATA #4 : unsigned integer, 8 bytes
4096
DATA #5 : String, 53 bytes
/mnt/logs/audit/temp_del_path/stmt_20251113131807.del
DATA #6 : String, 105 bytes
Search for ossError*Analysis probe point after this log entry for further
self-diagnosis of this problem.

Audit log entries might not be forwarded to the zen-audit service

Applies to: 5.3.0 and later

You might lose log entries when the log-streaming pod crashes or the audit log PVC is experiencing issues, resulting in logs not being forwarded to the IBM Software Hub audit service.

Data source and connection issues

For information about limitations and known issues that apply to data sources and connections, see Limitations and known issues for data sources in Data Virtualization.

Data virtualization issues

Incorrect column names might appear when you preview joined virtualized assets

Applies to: 5.3.0

When you join two virtualized assets, and then preview it, the column names displayed might be different from those in the original assets. This naming discrepancy impacts only the preview, and does not effect the final virtualized data objects, which will display the correct column names. There is no workaround.

RELOADTABLES API and the List view might be slow or might fail to fetch data if the schema, table, or column name contains wildcard characters

Applies to: 5.3.1

You might not see tables after you run the RELOADTABLES API or access the List view from the Virtualize page. When a schema, table, or column name contains wildcard characters such as an underscore (_) or percent sign (%), a wildcard search is performed instead of a literal search when fetching data. As a result, the execution phase might be slow or might fail in some cases.

Workaround: Configure schema filtering to limit the scope and speed up RELOADTABLES. You can set the RELOADTABLES_ALLTABS and RELOADTABLES_ALLCOLS filters using the SETCONFIGPROPERTY API on the Run SQL page. For schema, table, or column names that contain wildcards, ensure that you escape the wildcard characters using two backslashes (\). See also SETCONFIGPROPERTY properties.

In this example, hive_data is the catalog name and gosales_1021 is the schema but with an escaped underscore (gosales\\_1021):

call DVSYS.setconfigproperty('RELOADTABLES_ALLTABS_PREST10000','hive_data,gosales\\_1021,null,null','qpendpoint_1',?,?);
call DVSYS.setconfigproperty('RELOADTABLES_ALLCOLS_PREST10000','hive_data,gosales\\_1021,null,null','qpendpoint_1',?,?);

Users with a username that start with an underscore (_) are unable to access or query virtualized tables

Applies to: 5.3.0 and later

Despite being granted the required permissions, users that have a username that start with an underscore (_) are unable to access or query virtualized tables. If that user attempts to access virtualized tables, then this error displays:

Unexpected error code "58009" received from data source "QPLEX". Associated text and tokens are "Network protocol exception: DSS chained with same id at en".. SQLCODE=-1822, SQLSTATE= , DRIVER=4.32.28

Workaround: Create users with a username that do not begin with an underscore (_), then proceed to grant them permissions, and then attempt to access or query the tables again.

The List view might display additional tables

Applies to: 5.3.0 and later

If you added a datasource with personal credentials enabled on the platform connection, then the List view in the Virtualize page might display:

• • • Additional tables that the user might not have access to.
• All of the tables that the user has access to; however, these tables are not available for previewing or virtualizing.

The List view might not display the column name or type of some tables

Applies to: 5.3.0 and later

If you added a datasource with personal credentials enabled on the platform connection, then the column name and type metadata of some tables might not be displayed in the List view. However, you can still virtualize those tables and modify the metadata of the virtualized table by selecting Edit columns from the Review cart and Virtualize tables page.

The List view on the Virtualize page does not consistently display tables or views

Applies to: 5.3.0 and later

The List view does not accurately display the tables or views the user has access to for data sources that have personal credentials enabled. For data sources with personal credentials enabled, this issue occurs because the list view displays tables or views that are relevant to CCDEFINER user.

Workaround: Use the Explore view to view the tables and views that you have access to.

Recreating virtualized tables after using the DROP NICKNAME SQL statement results in object already exists error

Applies to: 5.3.0 and later

When you use the DROP NICKNAME SQL statement to drop tables that have a defined nickname, attempting to recreate and virtualize the tables in the Review cart and virtualize tables page results in an Object already exists error.

Workaround: Use the delete API to remove all the data that is associated with the virtualized tables, then attempt to virtualize the table again using the same nickname. The delete API does not indicate whether it ran successfully, and you might encounter an error. Regardless, you should attempt to virtualize the tables again. To use the delete API, you will need to get an authorization token. For more information, see Delete virtualized data and Get authorization token.

Data that is virtualized with double-byte coded character sets and special characters might appear truncated

Applies to: 5.3.0 and later

When you virtualize a table with a double-byte coded character set and special characters, such as Swedish characters, data might appear to be cut off.

Workaround: When virtualizing a table, use the Edit columns menu to extend the field lengths for those columns.

Virtualizing a table with many columns or long column names might fail

Applies to: 5.3.0 and later

Virtualizing some tables in Data Virtualization might fail with a Virtual table creation failed message. Some tables contain columns with large STRING and CLOB data. Virtualizing the table by reducing the column width or even choosing just one of the columns fails with an error message.

Workaround:

1. Set the remote schema filter to a schema where the large table does not exist so that it does not get cached.
2. Create the virtual table with a direct CREATE OR REPLACE NICKNAME statement that includes the SOURCELIST definition option as shown in the following example. The SOURCELIST value describes the remote location of the table to be virtualized in the format <CID>:<RemoteSchema>. The CID is the connection ID for the source and can be found in source details of the Data sources page, or in the result of select * from dvsys.listrdbc query.

   /* IBM_DVSYS */ CREATE OR REPLACE NICKNAME "ADMIN"."VERY_LARGE_TABLE" for QPLEX.gaiandb."VERY_LARGE_TABLE"
       ( 
           VERY_LONG_COLUMN_IDENTIFIER1,
           VERY_LONG_COLUMN_IDENTIFIER2,
           VERY_LONG_COLUMN_IDENTIFIER3,
           ...
           VERY_LONG_COLUMN_IDENTIFIER999,
           VERY_LONG_COLUMN_IDENTIFIER1000
   ) OPTIONS(SOURCELIST 'DB210000:DRV');
   

   
3. Query individual columns of the large virtual table.

   

4. Run aggregations and most other queries.
   Note:

   You cannot select all columns for the large table with a SELECT * statement. You see an error message that is similar to the following message.

   SQL5105N  The statement failed because a Big SQL component encountered an 
   error.  Component receiving the error: "DV-FMP".  Component returning the 
   error: "Virtualization Connector".  Log entry identifier: "GAI-001-NA".  
   Reason: "".  SQLSTATE=58040
   

Installation and upgrade issues

User and group management issues

Privileges and authorities that are granted to user groups are not considered when you create views

Applies to: 5.3.0 and later

Privileges and authorities that are granted to user groups are not considered when you create views. This limitation is a result of a Db2 limitation on groups.

Workaround: To workaround this issue, instead of granting access to specific groups from the Manage access page, you should grant access to the public by selecting All data virtualization users. Then create a new data protection rule to define Allow or Deny rules based on groups.

Data governance issues

RCAC data protection rules are not applied to a view if both Deny access and masking IBM Knowledge Catalog rules are applied to the table referenced by the view

Applies to: 5.3.0 and later

If a table has both the Deny access rule and external RCAC (column and row filters) IBM Knowledge Catalog data protection rules applied to it, then the RCAC rules are not applied to any views that reference that table, leaving the view unmasked.

Workaround:

Use Data Virtualization Db2 authorizations to deny access and define IBM Knowledge Catalog data protection rules to mask data and filter rows instead of doing both through IBM Knowledge Catalog data protection rules. For more information, see Authorization model for views.

You cannot apply business terms when you virtualize files in data sources on the Files tab

Applies to: 5.3.0 and later

When you virtualize files in Data > Data virtualization > Virtualize, the Business terms column is not available for data sources on the Files tab. These data sources do not support business terms.

You cannot see business term assignments or grouped tables in the Explore view

Applies to: 5.3.0 and later

On the Virtualize page, you cannot see business term assignments and you cannot see grouped tables.

Workaround: Switch to the List view to see business term assignments and grouped tables.

Cannot see list of available tables in the strict virtualization mode

Applies to: 5.3.0 and later

In the strict virtualization mode (where you can see tables only if they have at least one column with business term assignment), when you navigate to the Virtualize page, the console appears to be loading the table list for a while without showing any tables. The loading can be much slower compared to the default virtualization mode while the console evaluates the list of eligible tables that can be virtualized, depending on term assignments to data source table and column names.

A virtualized object cannot be used in Cognos Dashboards without credentials and an appropriate role

Applies to: 5.3.0 and later

Using a virtualized object in Data Virtualization displays an error message if you do not enter credentials for the Data Virtualization connection or you do not have the correct role.

If you did not enter a username and password when you created the connection to the Data Virtualization data source, you see the following error: Missing personal credentials. If you are not assigned the Admin or Steward role for this object, you see the following error: Unable to access this asset.

To work around this issue, see A virtualized object cannot be used in Cognos Dashboards without credentials and an appropriate role in Data Virtualization.

Caching issues

Online backup of Data Virtualization can affect cache refreshes

Applies to: 5.3.0 and later

If you schedule an online backup in Data Virtualization and if at the same time a cache refresh operation runs, the cache write operation can fail.

Online backup in Data Virtualization works by quiescing database write and update operations. Cache refresh is a write operation that updates Data Virtualization caches with fresh data from remote data sources. Both online backup and cache refresh operations can be scheduled to run periodically. These schedules can conflict and every time the cache tries to refresh, an online backup might be in progress or it might start while the cache refresh is in progress. In these scenarios, cache refresh operations can fail with an error similar to the following message. The cache is active but it contains stale data.

The statement failed because a Big SQL component encountered an error. 
Component receiving the error: "BigSQL IO". Component returning the error: "UNKNOWN". 
Log entry identifier: "[BSL-1-b1bf428f]". Reason: "Cannot add block to /warehouse".. 
SQLCODE=-5105, SQLSTATE=58040, DRIVER=4.27.25

Cache auto-refresh might also fail and you can either manually refresh or wait for the next auto-refresh. However, if the online backup is scheduled such that it conflicts with any cache's refresh schedule, then every auto-refresh of those caches will fail.

Workaround: Reschedule the cache's refresh or the online backup schedule to avoid conflicts. You can also refresh the cache manually at any time.

File issues

You might encounter errors when you virtualize large Excel files

Applies to: 5.3.0 and later

You might experience an error when you preview or virtualize large files with Excel format (XLS):

ERROR 400 'Your InputStream was neither an OLE2 stream nor an OOXML stream' was thrown while evaluating an expression.

Workaround: You can follow these steps:

1. Load the file data into a table on a supported data source.
2. Virtualize the table.
3. Optionally, you can change the format of the file; for example, to CSV format before you virtualize it again.

Encoding detection override for files data with Japanese characters

Applies to: 5.3.0 and later

For text files exposed by remote connectors, Cloud Pak for Data automatically detects the encoding scheme of flat data files, such as CSV and TSV files. However, to avoid decoding issues, it is recommended that you set the encoding scheme manually for flat data files.