StarQuest Technical Documents
StarQuest Data Replicator (SQDR) FAQs
Last Update: 15 April 2008
Product: StarQuest Data Replicator
Version: 3.4 or later
Article ID: SQV00DR006
Abstract
This article answers frequently asked questions (FAQs) about the StarQuest Data Replicator (SQDR). For a general overview of SQDR and system requirements, see the SQDR product page.
Questions
Can I perform incremental updates to a database after completing the initial bulk replication?
Is there any loss of transparency or loss of datatype information in the replication?
How does SQDR handle text fields in non-English languages?
Can I reformat the data in the process of replicating it?
How can I turn off subscription caching?
If I want to replicate between DB2 and Oracle, do I still need SQL Server?
Can I perform incremental updates to a database after completing the initial bulk replication?
With SQDR v3.1 StarQuest introduced the separately
licensed component, SQDR Plus, that provides incremental
replication support for SQDR users. Incremental
replication copies only the data that has changed, which
reduces the amount of data that is transferred and
allows the replication to occur more frequently.
Incremental replication requires installing the SQDR
Plus software on the host database system to
monitor changes and communicate with the Data Replicator
Windows-based service. SQDR Plus is currently supported
on iSeries and UDB for Windows systems.
Is there any loss of transparency or loss of data type information in the replication?
No, SQDR accesses host data through the ODBC interface, which supports most host data types and ranges of data values directly. When you configure a replication operation, SQDR queries the source database and automatically communicates data type and attribute information to the target database along with the actual data. You can also configure custom conversions for exceptional cases.
How does SQDR handle text fields in non-English languages?
SQDR supports textual data in all national languages, including Double Byte Character Set (DBCS) languages. It relies on the ODBC interface, along with host and client code page configuration to ensure a transparent mapping between EBCDIC and ASCII (or Unicode) representations of the text.
Can I reformat the data in the process of replicating it?
Yes, you can choose to skip certain rows or columns of the source table, and you can also specify computed columns based on other columns in the source data. These specifications can be made by using the built-in replication options or by using SQL (structured query language) during the replication configuration process.
Since the SQDR replication service requires unlimited access rights to my host data, isn't this a security risk?
SQDR fully supports your host's data access security. It accesses host data through an ODBC data source, and each data source is configured with a host user name and password. The host database administrator manages the access rights for this account to the host database, so SQDR can only perform operations on the database that are permitted by the host account.
Yes, SQDR can replicate LOB data to and from DB2, SQL Server, and Oracle data sources.
How can I turn off subscription caching?
SQDR will cache subscription information in memory to improve performance. It updates the information about the subscription when the SQDR service is stopped and restarted. It will also obtain the latest subscription information if the subscription properties have been changed. Add the subCacheLimit registry entry to the SQDR service registry key so that SQDR always retrieves new subscription information.
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that could require you to reinstall your operating system. Edit the registry at your own risk.
1. Open the Windows Registry Editor (regedit.exe).
2. Locate the key: HKEY_LOCAL_MACHINE\SOFTWARE\StarQuest\SQDRSVC.
3. Add a new String Value called "subCacheLimit" and set this value to -1.
Entry Name: subCacheLimit
Value: -1
4. Close the Registry Editor and stop and restart the Data Replicator service.
If I want to replicate between DB2 and Oracle, do I still need Microsoft SQL Server?
The Data Replicator requires a control database in which to store definitions for sources, destinations, and subscriptions. You can use any of the following editions of SQL Server for the SQDR control database.
-
SQL Server 2000 Desktop Engine (MSDE 2000) Release A, or MSDE 2000 SP3a or SP4
-
SQL Server 2000 with SP3a or SP4
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SQL Server 2005 or SQL Server 2005 Express Edition
If you do not already have a SQL Server installation, you can obtain the MSDE 2000 or SQL Server 2005 Express Edition free of charge from Microsoft. Refer to the StarQuest technical document "Installing SQL Server for a Control Database" for more information about using these versions of SQL Server as a control database for the Data Replicator.