User FAQs

 

You need to consider these conditions when working with another specific IBM^® product.

This topic collection has concentrated on describing i5/OS^® support for distributed relational databases in a network of System i™ products (a like environment). However, many distributed relational database implementations exist in a network of different DRDA-supporting platforms.

This topic provides a list of tips and techniques you might need to consider when using the System i product in an unlike DRDA^® environment. It is not intended to be a comprehensive list. Many problems or conditions like the ones described here depend significantly on your application. You can get more information about the differences between the various IBM platforms from the IBM SQL Reference Volume 2, SC26-8416, or the DRDA Application Programming Guide, SC26-4773.

• Connecting to a distributed relational database
  When you connect from an application requester (AR) other than System i to a DB2 Universal Database™ for iSeries™ application server (AS), columns tagged with CCSID 65535 are not converted. If the files that contain these columns do not contain any columns that have a CCSID explicitly identified, the CCSID of all character columns can be changed to another CCSID value. To change the CCSID, use the Change Physical File (CHGPF) command. If you have logical files built over the physical file, follow the directions given in the recovery topic of the error message (CPD322D) that you get.

• i5/OS system value QCCSID
  The default system value for QCCSID (coded character set identifier) is 65535.

• CCSID conversion considerations for DB2 UDB for z/OS and DB2 UDB server for VM database managers
  One of the differences between a DB2 Universal Database for iSeries and other DB2^® databases is that the i5/OS operating system supports a larger set of CCSIDs. This can lead to errors when the other database managers attempt to perform character conversion on the data (SQLCODE –332 and SQLSTATE 57017).

• Why am I getting an SQL5048N message when I attempt to connect from DB2 for Linux, UNIX, and Windows?
  The definition of message SQL5048N states that the release level of the database client is not supported by the release level of the database server. However, the message can sometimes be misleading.

• Do i5/OS files have to be journaled?
  Journaling is not required if the client application is using an isolation level of no-commit (NC) or uncommitted read (UR), and if the DB2 UDB SQL function determines that the query data can be blocked. In that case commitment control is not enabled, which makes journaling unnecessary.

• When will query data be blocked for better performance?
  The query data will be blocked if none of these conditions are true.

• How do you interpret an SQLCODE and the associated tokens reported in an SQL0969N error message?
  The client support used with DB2 for Linux^®, UNIX^®, and Windows^® returns message SQL0969N when reporting host SQLCODEs and tokens for which it has no equivalent code.

• How can the host variable type in WHERE clauses affect performance?
  One potential source of performance degradation on the i5/OS operating system is the client's use in a C program of a floating-point variable for a comparison in the WHERE clause of a SELECT statement.

• Can I use a library list for resolving unqualified table and view names?
  The i5/OS operating system supports a limited capability to use the operating system naming option when accessing DB2 Universal Database for iSeries data from a DRDA client program other than System i, such as those that use the DB2 for Linux, UNIX, and Windows product.

• Can a DB2 for Linux, UNIX, and Windows user specify that the NLSS sort sequence table of the DRDA job on i5/OS be used instead of the usual EBCDIC sequence?
  The i5/OS operating system recognizes a generic bind option. If you want to run a program from clients that support generic bind options, such as DB2 for Linux, UNIX, and Windows, you can request that i5/OS use the NLSS sort sequence associated with the corresponding DRDA server job.

• Why are no rows returned when I perform a query?
  One potential cause of this problem is a failure to add an entry for the System i platform in the DB2 for Linux, UNIX, and Windows Database Communication Services directory.

• What level of DB2 for Linux, UNIX, and Windows is required to interact with DB2 for iSeries?
  These FixPaks are required for interaction.

• How can I get scrollable cursor support enabled from DB2 for Linux, UNIX, and Windows to the System i platform?
  You must be using FixPak 4 or later on the client.

• Other tips for interoperating in unlike environments
  This topic collection provides additional information for using DB2 Universal Database for iSeries with DB2 for Linux, UNIX, and Windows. These tips were developed from experiences testing with the products on an OS/2^® platform, but it is believed that they apply to all environments to which they have been ported.

 

Parent topic:

Distributed database programming

 

Related reference

i5/OS support