Techniques related to a domain-specific language for transformations are disclosed. A server computer may process a table definition composed in a domain-specific language. The table definition may include a sequence of one or more transformations to be performed on one or more source tables to generate a target table. The sequence may include a customized transformation. A source dataset may be provided as input to an implementation of the customized transformation. An output dataset may be generated as a result of executing the implementation. An intermediate table may be generated based on performing at least one transformation on a particular source table. A supplemental portion for the intermediate table may be generated based on performing the at least one transformation on an appended portion of the particular source table. The target table may be generated based on combining the supplemental portion with the intermediate table.