Sybase ASE as Source

Capture

This section describes the configuration requirements for capturing changes from Sybase ASE. Data Source Solutions DSS only supports capture changes from a Sybase ASE database on Linux. For the list of supported Sybase ASE versions, from which DSS can capture changes, see Capture changes from location in Capabilities.

Table Types

DSS does not support capture from compressed tables in Sybase ASE.

Capture Methods

DSS allows the following methods for capturing (Capture) changes from Sybase ASE:

Direct Transaction Log Access

In this capture method (Capture_Method=DIRECT), DSS reads transaction log records directly from the database log device using the file I/O. This capture method is faster and less resource-intensive when capturing changes from database locations, especially for highly loaded databases. The DIRECT capture method and pipelined execution ensure optimum efficiency to keep up with the database log writers. As a result, when capture runs continuously, it will be capturing from the tail end of the log where the log writer(s) are writing.

The DIRECT capture method requires the following:

• DSS Agent must be installed on the Sybase ASE source database server. For the steps to install DSS Agent, see Installing DSS Agent.
• For Sybase ASE databases where the log is stored on a separate log device, an OS user who runs DSS must have direct read access to log device files. For 'mixed data and log' Sybase ASE databases, the OS user must have direct read access to data device files.

Archive Only

In this capture method (Capture_Method=ARCHIVE_ONLY), DSS reads/captures changes from Sybase ASE transaction dump (log backup) files available in the directory specified in the location property TRANSACTION DUMP DIRECTORY (Archive_Log_Path). Optionally, DSS can be configured to consider only the files that match the format defined in the location property FILENAME FORMAT (Archive_Log_Format). For more information, see section Accessing Transaction Dumps.

Grants for Capture

This section lists the grants/permissions required for capturing changes from Sybase ASE. The grants are applicable for all the capture methods listed above.

Based on your requirement, either of the permissions listed in this section can be used. For simplicity, we have categorized the required permissions into the following two models:

SysAdmin

In this permission model, the DSS database User must be granted the sa_role and sybase_ts_role roles. The benefit of this permission model is that it is easy to set up, there is no need for operators to install the stored procedures and perform any special SQL statements manually.

Minimal

In this permission model, the DSS database User is not granted or does not require sa_role and sybase_ts_role roles at runtime. The benefit of this permission model is the ability to run DSS with minimal database privileges.

Following are the configuration requirements that must be met/performed for this permission model:

• A user with sa_role and sybase_ts_role roles must install special stored procedures in the capture database using the script file dsssybaseprocs.sql available in the DSS_HOME/dbms/sybase/ directory.

• The DSS database User must be granted the following privileges:

  grant select on <em>table1</em>, <em>table2</em>,... to<em>username</em>
  
  grant execute on dss_traceon to <em>username</em>
  
  grant execute on dss_page to <em>username</em>
  
  grant execute on dss_logtail to <em>username</em>
  
  grant role replication_role to <em>username</em>
  

Supplemental Logging

Transaction logs are generally used for database recovery and normally Sybase ASE only logs data that is needed for recovery. For DSS to perform log-based capture, Sybase ASE needs to write some additional information into the transaction log, which is referred to as "Supplemental Logging" in DSS.

To enable Supplemental Logging, it is required to enable replication for the table(s) on Sybase ASE. DSS will automatically enable/disable replication for tables during Activate Replication/Deactivate Replication respectively. Also, this is the recommended method for enabling/disabling replication for tables on Sybase ASE.

Secondary Log Truncation Point

The location property Use Secondary Truncation Point (Log_Truncater) specifies who advances the Sybase ASE transaction log truncation point (truncates the log).

Supported log truncater method

• CAP_JOB_RETAIN: This method ensures Sybase ASE transactions are always available for DSS. Log device usage will grow if the capture job is idle. Not using truncation points allows multiple systems to capture from the same database, but the user must ensure that older transaction files are kept available as transaction dumps until they are replicated.

Accessing Transaction Dumps

Transaction dumps are the incremental backups of the transaction log. They can be very useful as an alternate to full database dumps.

• When the Capture_Method is set to ARCHIVE_ONLY, DSS reads/captures changes from Sybase ASE transaction dump.
• When the Capture_Method is set to DIRECT or SQL and if this location property TRANSACTION DUMP DIRECTORY (Archive_Log_Path) is defined, DSS will search for backups in this directory if the online log is truncated and no longer contains the log records needed for reading.

Transaction Dump Directory

DSS will search for the log backups in the directory in addition to the default log backup location for the source database. For versions prior to 6.1.1/0 and 6.1.0/1, DSS will search for the log backups only in the specified directory instead of the default log backup location for the source database.

FileName Format

This field/property describes the filename format (template) of the transaction log archive files stored in the TRANSACTION DUMP DIRECTORY (Archive_Log_Path). DSS will scan/consider only the files that match the format defined in this field/property.

This field accepts the following format variables:

• * - wildcard, matches zero or more characters
• ? - matches any single character

This field is optional. When this field is not defined, by default DSS will scan all files available in the TRANSACTION DUMP DIRECTORY.

Capturing from SAP Source

DSS allows you to capture changes from a Sybase ASE database which is used by an SAP ECC system. To enable capture using SAP dictionary, the location property SAP Source (SAP_Source_Schema) must be defined while creating a location or by editing the existing location's source and target properties. Then while adding tables to a channel, the Table Selection dialog will display the SAP tables defined in the SAP dictionaries.

When SAP pool, cluster, and long text (STXL) tables are added to a channel using the Table Selection dialog, the following actions are automatically defined:

• TableProperties with parameters PackedInside, CoerceErrorPolicy, and CoerceErrorType

• For each container (pool/cluster) table a separate action TableProperties is defined.

  • This action is not defined for long text (STXL) tables.