Concept

Template Driven Extraction (TDE) enables you to define a relational lens over your document data, so you can query parts of your data using SQL or the Optic API. Templates let you specify which parts of documents make up rows in a view. You can also use templates to define a semantic lens, specifying which values from a document make up triples in the triple index.

TDE enables you to generate rows and triples from ingested documents based on predefined templates that describe the following:

• The input data to match
• The data transformations that apply to the matched data
• The final data projections that are translated into indexed data

TDE enables you to access the data in your documents in several ways, without changing the documents themselves. A relational lens is useful when you want to let SQL-savvy users access your data and when users want to create reports and visualizations using tools that communicate using SQL. It is also useful when you want to join entities and perform aggregates across documents. A semantic lens is useful when your documents contain some data that is naturally represented and queried as triples, using SPARQL.

TDE is applied during indexing at ingestion time and serves the following purposes:

• SQL/Relation indexing. TDE allows the user to map parts of an XML or JSON document into SQL rows. With a TDE template instance, users can create different rows and describe how each column in a row is constructed using the extracted data from a document. For details, see Creating Template Views in the SQL Data Modeling Guide.
• Custom Embedded Triple Extraction. TDE enables users to ingest triples that do not follow the sem:triple schema. A user can define many triple projections in a single template, where each projection specifies the different parts of a document that are mapped to subjects, predicates or objects. For details, see Using a Template to Identify Triples in a Document in the Semantics Developer’s Guide.
• Entity Services Data Models. For details, see Creating and Managing Models in the Entity Services Developer’s Guide.

TDE data is also used by the Optic API, as described in Optic API for Multi-Model Data Access.