Migrating mappings
Migrating mappings allows you to:
- Export mapping metadata and mappings from a Compose project to CSV files. Mapping metadata will be exported to mappingsMetadata.csv while mappings will be exported to mappings.csv. The former shows the table mappings while the latter show the column mappings.
-
Import new mappings that do not exist in the current Compose project.
- Reuse the same mappings across several projects or Compose installations.
Mappings export guidelines
When exporting mappings and mapping metadata from Compose, it is important to note the following:
- The export of mappings is allowed for users with the Viewer security role.
- The order of writing the mapping metadata is according to metadata name alphabetically (e.g. Map_Orders appears after Map_Customers).
- The order of writing a mapping is according to target columns (same as Model ordinal).
- Source columns which are not mapped to anything will not appear in the exported file.
- All target columns will appear in the mappings even if they were not mapped.
Mappings import guidelines
When importing mappings and metadata to the Model, it is important to note the following:
- If required, you can import one CSV file at a time: mappingsMetadata.csv or mappings.csv.
- Column order has no meaning; only column names (case insensitive).
- When importing metadata, Compose validates that the targets exist in the Model. Source columns are not validated on import.
- If the source schema, table, view or query don't exist, they will be validated after the import.
- Importing mappings will fail in the following scenarios:
- If the target entity doesn't exist in the Model.
- If the compose database object doesn't exist.
- If the mapping attribute doesn't exist in the Model.
Valid CSV file formats
The CSV files must be in a valid format. For more detailed information, see the notes in Valid CSV file formats.
Mapping metadata CSV file format
| Column Name | Required | If column is missing | If value is missing | Comments |
|---|---|---|---|---|
|
Name |
Yes |
Reject |
Reject |
Case insensitive |
|
Landing Zone Database |
Yes |
Reject |
Reject |
The Compose "source database" name (excluding the word "landing") |
|
Schema |
No |
If there is no Schema column, either the default schema will be used or none (as some databases do not have separate schemas) |
If no schema is specified, either the default schema will be used or none (as some databases do not have separate schemas) |
- |
|
Source Type |
No |
Table | Reject |
Table/View/Query |
|
Source Object |
Yes |
Reject | Reject |
If Source Type is Table or View, the Source Object is its name. If Source Type is Query, the rules and limitations described in Valid CSV file formats will be applied. |
|
Target Entity |
Yes |
Reject | Reject | - |
|
Filter |
No |
No filter |
No filter |
|
|
Filter Params |
No |
Same name for attribute-parameter, like expression below |
Same name for attribute-parameter, like expression below |
Example of Semicolon parameters mappings: x1:unit >price;x2:quantity |
|
Mapping Name |
Yes |
Reject |
Reject |
Case insensitive |
|
Target Column |
Yes |
Reject |
No mapping if there is also no expression or lookup. |
Case insensitive |
|
Mapping Type |
No |
Field mapping |
Allow the field to be empty if there is no field mapping, no expression, and no lookup. |
Field Mapping /Expression/Lookup |
|
Field Mapping |
No |
Reject |
No mapping to this attribute. |
The name of the source field, or empty if this field is not mapped. |
|
Expression |
No |
No expression |
No expression in this attribute. |
Example of an expression value: ${x1}*${x2} |
|
Expression Params |
No |
All attribute-parameter mapping is trivial (same name) |
No expression in that attribute |
Example of Semicolon parameters mappings: x1:unit >price;x2:quantity |
|
Lookup Landing Database |
No |
No lookups |
No expression in that attribute |
Lookup Landing Database name Example: Northwind on MySQL |
|
Lookup Table |
No |
No lookups |
No expression in that attribute |
Lookup table or view name in schema table format. Example: Schema1.Orders |
|
Lookup Type |
No |
No lookups |
No expression in that attribute |
Table or View |
|
Lookup Condition Value |
No |
No lookups |
No expression in that attribute |
- |
|
Lookup Condition Params |
No |
No lookups |
No expression in that attribute |
Include Lookup/Landing. Example: x:$Lookup$.a;y:$Landing$.CustomerID |
|
Lookup Result Value |
No |
No lookups |
No expression in that attribute |
- |
|
Lookup Result Params |
No |
No lookups |
No expression in that attribute |
Same format as the lookup condition parameters. |