rs_subcmp Performance Enhancement

Hash algorithm improves the performance of rs_subcmp and compresses the data in primary and replicated tables.

The compressed data is then fetched by rs_subcmp.

Instead of taking the entire row of data during comparison between the primary table and replicated table, rs_subcmp now transfers only the compressed data of each data row from the primary or replicated tables, and then verifies or reconciles inconsistencies between them.

For an improved rs_subcmp performance, use the command line parameters -h or -H or their equivalent configuration file parameters FASTCMP or HASH_OPTION.

Note: To support hash algorithm, rs_subcmp requires ASE 15.0.2 or later and cannot handle case-sensitive comparison. It also cannot handle text, unitext, or image datatypes and does not allow the user to specify the precision for the float datatype (maximum precision is used). Also, Sybase suggests to set the ASE parameter default data cache to 128M or higher to get a better comparison performance.

The rs_subcmp program has a large number of options, which you can specify on the command line or in a configuration file. See Replication Server Reference Manual > Executable Programs > rs_subcmp for a list of these configuration file parameters and command line options.