Limiting Records to Compare

To compare two sets data groups, all records in two sets of data groups are loaded into memory for comparing by default. The computer processor need process all records record by records, columns by columns in both sets of tables to get comparison result. The comparison process uses a lot of resources in your computer and it might take a long time to finish the comparing work. The comparing process could be failed by running out of resources on your computer, for example, running out of memory. The usage of memory of your computer depends on number of records in two sets of comparing data groups and the size of the each record. So, limiting number of records to compare for SQLDBCompare is crucial for comparing tables that have a lot of records.

The command line data comparing uses less resources than the Windows based program. It can compare more data records than the Windows based counter part. To limit number of records to compare, you can specify a "WHERE..." statement or use "TOP xxxx" statement right after the SELECT statement in the query. When you need to compare data in very large quantity, you can query the total number of the data records that you need to compare. Then, you can break the large data records comparison into multiple smaller comparisons.

Figure 1 Limit Number of Records for Comparison