Increase the queue block
size to improve replication performance.
The
queue block size is the number of bytes in a contiguous block of
memory used by stable queue structures. Setting a larger queue
block size allows Replication Server to process more
transactions in a single block. A larger queue block size also
allows the inbound SQM thread to allocate segments less
frequently, and therefore reduces the time that the EXEC thread
needs to wait for the SQM thread to be ready to receive data
from the EXEC thread.You can increase the queue block size from
the default of 16KB to 32KB, 64KB, 128KB, or 256KB. Performance
improvement is also dependent on the transaction profile and the
environment.
Note: You must have the Advanced Services Options license, named REP_HVAR_ASE, to use the increase queue block size feature.
Recommendations
Sybase strongly recommends that you:
- Verify you have sufficient memory before you increase the queue block size.
- Experiment with different queue block sizes to determine the optimum value for your replication system.
Restrictions
- Make sure that there is no data flowing into Replication Server while the queue block size change is in progress.
- You cannot change the queue block size while a subscription is being materialized, if dematerialization is in progress, or if routes are being created or destroyed. The queue block size change terminates with an error message while Replication Server continues operating.
- Once you start the procedure to change the queue block size, Replication Server does not accept another command to change the queue block size until the first change is completed.
- Do not use any other procedures to change the queue block size in the RSSD directly, as these procedures may result in inconsistencies in the queue block size configuration and cause Replication Server to shut down.
Note: All queues are drained after the block size changes.