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English
  • Data Replication 9.8.0
  • All Products

Table of Contents

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  1. Preface
  2. Data Replication Overview
  3. Understanding Data Replication
  4. Sources - Preparation and Replication Considerations
  5. Targets - Preparation and Replication Considerations
  6. Starting the Server Manager
  7. Getting Started with the Data Replication Console
  8. Defining and Managing Server Manager Main Servers and Subservers
  9. Creating and Managing User Accounts
  10. Creating and Managing Connections
  11. Creating Replication Configurations
  12. Materializing Targets with InitialSync
  13. Scheduling and Running Replication Tasks
  14. Implementing Advanced Replication Topologies
  15. Monitoring Data Replication
  16. Managing Replication Configurations
  17. Handling Replication Environment Changes and Failures
  18. Troubleshooting
  19. Data Replication Files and Subdirectories
  20. Data Replication Runtime Parameters
  21. Command Line Parameters for Data Replication Components
  22. Updating Configurations in the Replication Configuration CLI
  23. DDL Statements for Manually Creating Recovery Tables
  24. Sample Scripts for Enabling or Disabling SQL Server Change Data Capture
  25. Glossary

User Guide

User Guide

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Examples of Setting the Start Point

Examples of Setting the Start Point

Review the following examples to learn how to set the Start Point value to customize where the Extractor begins processing in the logs.
These examples are based on the following assumptions:
  • You have a Microsoft SQL Server source.
    To apply these examples to other source types, use the LSN
    , log coordinate,
     or SCN format that is appropriate for the source type.
  • The
    Extract Range
     tab identifies a set of transaction logs with a lowest LSN value of 38000000001600001.
  • The
    extract.process_old_logs
     runtime parameter is set to 0.
  • When InitialSync completed processing, it wrote a Sync LSN value of 38000000035400132 to the configuration. Later, you specified a Start LSN value on the
    Map Tables
     tab. When the Extractor starts processing the logs, it begins from the Start LSN that you specified.

Example 1. Default LSN

You specify an LSN value of -1 for the Start Point.
The Extractor starts reading the transaction log from the default start LSN.
For all sources, enter -1 to specify the default Start Point value.

Example 2. Start LSN Lower than the Lowest LSN

For the Start Point, you specify an LSN value of 37000000063700250, which is lower than the lowest available LSN of 38000000001600001.
The transaction log that contains the specified start LSN is not available. However, a transaction log that contains higher LSN values is available. In this case, the Extractor ends with the following error message: 
The transaction log that contains the LSN 37000000063700250 from which the Extractor must start reading the database logs is not available. The lowest available LSN is 38000000001600001 (database ID 5.)

Example 3. Start LSN Greater Than the Current LSN

For the Start Point, you specify an LSN value of 39000000067800137, which is greater than the current LSN of 39000000037800272.
The transaction log that contains the specified start LSN is not yet available. However, a transaction log that contains lower LSN values is available. In this case, the Extractor does not extract any data and ends successfully. When log records with an LSN that is equal to or greater than 39000000067800137 appear in the log, the Extractor extracts these records and writes them to intermediate files.

Example 4. Start LSN Greater Than the Sync LSN

For the Start Point, you specify an LSN value of 38000000039900002, which is greater than the Sync LSN of 38000000035400132.
The Extractor extracts changes starting from the specified start LSN. The Extractor does not extract the changes that occurred after initial synchronization and before the specified start LSN.
Use this scenario to reduce Extractor processing time if the changes that occurred between initial synchronization and the start LSN are not for mapped tables.
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