Before running the compare or repair commands, review these guidelines.
The following are commonly modified compare and repair parameters. Do not increase the values unless necessary. For details about these parameters, see their documentation in the SharePlex Reference Guide.
This parameter controls the fetch batch size. The batch size controls the number of rows that SharePlex selects at once for comparison. Larger batch sizes increase processing speed but require more memory. The value is divided equally by the number of compare threads to be used, and then the batch size is recalculated based on all column sizes added together.
This parameter manages the select statement Degree of Parallelism hint. The parallelism option of the command overrides this setting.
|SP_DEQ_PART_TABLE_UPDATE||This parameter controls how the repair commands work on Oracle partitioned tables, depending on whether row movement is possible.|
|SP_DEQ_READ_BUFFER_SIZE||This parameter controls the size of the buffer that holds fetched LONG and LOB data and can be adjusted based on available system memory.|
|SP_DEQ_ROW_LOCK_THRESHOLD||This parameter sets a threshold that controls whether SharePlex uses row-level or table-level locking when a where option is used.|
This parameter determines whether or not LOBs are included in the compare/repair processing.
Set this parameter on the source system.
|SP_DEQ_TIMEOUT||This parameter sets a queue backlog threshold. High backlogs delay the establishment of a connection between the source and target compare/repair processes. If the backlog meets or exceeds this value, any compare or repair command that is issued on the source will exit and return an error. If this happens, consider running the compare or repair when the system is less busy.|
The recommended procedure for maintaining synchronized data through the comparison and repair commands is to run the compare or compare using command first, then view the results with the repair status command. This command shows any rows that are out-of-sync and the possible cause. Unless the cause of the out-of-sync condition is corrected, replication will go out of synchronization again, even if you repair the rows this time. After the problem is fixed, issue the repair or repair using command.
You can run the repair or repair using command without doing a preliminary comparison. The command performs a comparison first, to identify the out-of-sync rows, and then it repairs those rows. However, the underlying cause of the out-of-sync condition must be corrected to prevent future out-of-sync conditions.
See for causes and solutions for out-of-sync conditions.
To view the status or results of a comparison, use the compare status command in sp_ctrl.
To view the status or results of a repair, use the repair status command in sp_ctrl.
The best time to repair a target table depends on its size, the cause of the problem, the extent of out-of-sync rows, and how long you are willing to tolerate users being locked out. Before you initiate a repair, consider the following:
If you must repair a table immediately, but cannot tolerate locks or replication latency, you can use the where option to limit the repair to certain rows. An alternative is to use the key option, but this option may cause the repair to miss some out-of-sync rows.
To get additional information and syntax for the compare and repair commands, see the command documentation in the SharePlex Reference Guide.
This chapter contains instructions for improving the performance of the Capture process to prevent Capture from losing pace with the volume of redo that an Oracle source database generates.
If you have PK/UK logging enabled on the source database (recommended to support more SharePlex features and faster processing), check the setting of the SP_OCT_ENABLE_LOBMAP parameter. This parameter controls whether or not SharePlex uses a LOB map when replicating tables that contain out-of-row LOB columns. The LOB map is used by the Capture process to map LOBIDs and rows when PK/UK logging is not enabled. LOB mapping is enabled by default. The SHAREPLEX_LOBMAP table stores these mappings.Transactions with numerous LOB operations can slow down Capture because it needs to maintain and refer to the mappings. If PK/UK logging is enabled on the database, you can disable LOB mapping by setting this parameter to 0.
To disable LOB mapping during active replication
Set SP_OCT_ENABLE_LOBMAP to 0.
sp_ctrl> set param SP_OCT_ENABLE_LOBMAP 0
sp_ctrl> stop capture
sp_ctrl> start capture