Some data flow processes are not harvestable using the bridges. If these processed are not modeled in Talend Data Catalog, it will leave gaps in the lineage and impact analysis answers and provide an incomplete picture of the physical architecture of your systems.
Data mapping specifications are high-level logical definitions of the way data "flows" from some number of source models into elements of a target model.
These mappings are specified using a simple web based drag and drop type mapping specification editor. They are defined using descriptive text. You may also define pseudo operations using an operation editor.
- A query mapping is most flexible. You define a column by column mapping definition for
all the columns in the target table. They can include joins, filters, transformations,
etc. Each query mapping is defined for one target classifier.
When defining a query mapping, the target classifier can come from any data store model defined in the configuration. Sources can come from any data store model(s), and as you can have many source classifiers, they could come from multiple source contents in the same mapping.
- A bulk mapping is assumed to be for source and target tables which have matching columns names or positions. You can certainly define filters, therefore the mappings at the column level are simple and name or position matching. Each bulk mapping is defined for one target schema and one source schema.