Use rs_subcmp To Locate and Correct Inconsistencies

Use the rs_subcmp standalone executable program to compare a replicate table to the primary version of the table, find—and correct if you so choose—missing, orphaned, and inconsistent rows in Sybase databases.

On UNIX systems, the program is called rs_subcmp. On PC systems, the program is called subcmp. The rs_subcmp program is located in the bin subdirectory of the Sybase release directory. Refer to the Replication Server installation and configuration guides for your platform for more information.

The program works by logging in to the primary data server and the replicate data server, and selecting and comparing rows from both tables.

Because some differences between primary and replicate data can be attributed to latency, rs_subcmp first identifies inconsistencies, and then performs iterations a specified number of times. rs_subcmp waits for any updates to be replicated before removing the corrected rows from its list.

It is best to use rs_subcmp when latency is low to avoid the program having to perform several iterations through the data.

You can instruct rs_subcmp to display inconsistent rows on the standard output, correct them, or both display and correct them.

Creating a configuration file avoids the need for complex command lines, which are prone to errors. Here is an rs_subcmp configuration file that compares the sales table in the pubs2 database in the data servers TOKYO_DS and SYDNEY_DS:

PDS=TOKYO_DS
RDS=SYDNEY_DS
PDB=pubs2
RDB=pubs2
RTABLE=sales
RSELECT=select * from sales \
		order by stor_id, ord_num
RUSER=sa
KEY=stor_id
KEY=ord_num
RECONCILE=Y
RECONCILE_CHECK=Y
WAIT=15
NUM_TRIES=5
VISUAL=Y

The PTABLE, PSELECT, and PUSER parameters, which are used for the primary database, are not shown in this example. Their values are the same as those of corresponding parameters in the replicate databases, so they need not be included in the configuration file.

The RSELECT line and the PSELECT line (if used) must be entered on one line. To continue a line onto the next line (row), precede each newline character with a backslash as, for example:

RSELECT=select * from sales \
		order by stor_id, ord_num

Note: Due to update filtering, columns of rs_address datatype may not be identical between the primary and replicate databases. Do not select rs_address columns using RSELECT or PSELECT parameters.

When you execute rs_subcmp, you can override values in the configuration file with command line options. For example, rather than changing the name of the TOKYO_DS data server to TOKYO_DS2 in the configuration file, you can specify it on the command line, using the -S flag, as the following example illustrates:

rs_subcmp -f sales_cmp -S TOKYO_DS2 > sales_badrows

In this example, the -f option specifies a configuration file name, sales_cmp. If the VISUAL parameter is set to “Y” in the configuration file (equivalent to the -V command line option), a list of the inconsistent rows is generated. In this example, the output is redirected to a file.