A compare is a data operation that will search and show difference between data resources.
The comparison may be performed:
- at the metadata level, meaning
- on the data resource attributes
- on the data structure
- or and at the data level record by record
Command and Arguments
The compare operation is supported by the data compare command
Data Selector (Source)
The data selector can choose any content resource such as:
- The target uri may be not given as argument. If this is the case, the comparison will except an empty target.
The report-level argument defines what the command will return:
- resource - a comparison report will be created for all comparison
- record - a comparison report will be created for each comparison and the record data comparison will be available
- all - all type of comparison report will be created
The data-source defines the origin of the data to compare.
- content - the default - the data to compare will be the records
- structure - the data to compare will be the column definitions.
Unique Columns / Driver Columns
The unique columns (driver columns) are the columns that drives the comparison process.
For instance, if you compare two resources that have an unique id column,
- if the comparison has fetched:
- a source record with a id value of 1
- a target record with a id value of 2
- the comparator will:
- mark the source record has missing in the target
- fetch records only from the source until it finds the record with the id 2 or above.