RTL Configuration

Once you alter the connection to Sybase IQ and set dsi_compile_enable on, you can also use parameters to determine when to start and stop transaction grouping and compilation.

dsi_compile_max_cmds – specifies, in number of commands, the maximum size of a group of transactions. When RTL reaches the maximum group size for the current group that it is compiling, RTL starts a new group.

If there is no more data to read, and even if the group does not reach the maximum number of commands, RTL completes grouping the current set of transactions into the current group. The default is 100,000 commands.
dsi_bulk_threshold – specifies the number of net row change commands after compilation has occurred on a table for a command type, that when reached, triggers Replication Server to use bulk copy-in on that table for the same command type. The default is 20 net row change commands.
dsi_command_convert – specifies how to convert a replicate command. A combination of these operations specifies the type of conversion:
- d – delete
- i – insert
- u – update
- t – truncate
- none – no operation
Combinations of operations for dsi_command_convert include i2none, u2none, d2none, i2di, t2none, and u2di. The operation before conversion precedes the “2” and the operations after conversion are after the “2”. For example:
- d2none – do not replicate the delete command. With this option, you do not need to customize the rs_delete function string if you do not want to replicate delete operations.
- i2di,u2di – convert both insert and update to delete followed by insert, which is equivalent to an autocorrection. If you disable row count validation by setting dsi_row_count _validation off, Sybase recommends that you set dsi_command_convert to i2di,u2di to avoid duplicate key errors and allow autosynschronization of databases during replication.
- t2none – do not replicate the truncate table command.
The default for dsi_command_convert is none, which means there is no command conversion.
dsi_compile_retry_threshold – specifies a threshold value for the number of commands in a group. Replication Server 15.6 includes the dsi_compile_retry_threshold parameter as part of enhancements to the retry mechanism.

RTL automatically sets the Sybase-recommended default values for dsi_compile_max_cmds, dsi_bulk_threshold, dsi_command_convert, and dsi_compile_retry_threshold. However, you can specify your own values to tune performance in your replication environment. For example, after you enable RTL, you can set different values for the parameters:

alter connection to IQSRVR.iqdb
set dsi_compile_max_cmds to ‘50000’
go

alter connection to IQSRVR.iqdb
set dsi_bulk_threshold to ‘15’
go

alter connection to IQSRVR.iqdb
set dsi_command_convert to ‘i2di,u2di’
go

alter connection to IQSRVR.iqdb
set dsi_compile_retry_threshold to '200'
go

Note: You must execute a separate alter connection command for each parameter you want to change. Do not enter more than one parameter after entering alter connection.

See "alter connection," in Chapter 3, "Replication Server Commands" in the Replication Server Reference Manual for full descriptions of dsi_compile_max_cmds, dsi_bulk_threshold, and dsi_command_convert.