Enhanced DSI Efficiency

Enabling dsi_cmd_prefetch reduces data replication latency which decreases the length of time that Replication Server waits for results from the replicate data server through the ct_results routine, and subsequently reduces the length of time the data server waits for Replication Server.

dsi_cmd_prefetch works by :

Allowing Replication Server to prepare the next batch of commands for the replicate data server before Replication Server processes results of the current batch from the replicate data server.
Improving concurrency between the DSI executor (DSI/E) and DSI scheduler (DSI/S) threads.

Set dsi_cmd_prefetch on with alter connection or create connection.

For example, to enable dsi_cmd_prefetch for the connection to the pubs2 database in the SYDNEY_DS data server, enter:

alter connection to SYDNEY_DS.pubs2
set dsi_cmd_prefetch to ‘on’

Default: off.

dsi_cmd_prefetch is a dynamic parameter. You need not suspend and resume the database connection after you enable the parameter for the change to take effect.

If you also tune your data server to enhance performance, you may gain an additional performance increase when you enable dsi_cmd_prefetch.

Note: When you set dsi_compile_enable to ‘on’, Replication Server ignores what you set for dsi_cmd_prefetch.