andmeskeemide

Andmeskeemide (Estonian for data schemas) are formal descriptions of the structure and constraints of data used by information systems. They specify what data can exist, how it is organized, and how data items relate to one another. Data schemas support data quality, interoperability, and efficient storage by providing a common understanding of data across applications and processes.

A typical data schema identifies entities or tables, fields or attributes, data types, allowed values, and relationships such as keys and cardinalities. It may also define constraints, such as primary keys, foreign keys, unique constraints, and validation rules. Schemas are often described at multiple levels: conceptual schemas present a high-level view of the domain; logical schemas adapt the model to a database technology (for example relational); physical schemas specify storage details like table structures, indexes, and partitioning.

Common representations include Entity-Relationship diagrams, UML class diagrams, and schema language definitions in SQL (DDL), JSON Schema, XML Schema, or RDF/OWL. In traditional relational databases the schema is implemented in the database's catalog; in modern data platforms schemas may accompany data in data lakes, data warehouses, or API specifications.

Schema design supports data governance, validation, and data integration by ensuring consistent interpretation of data across systems. Schema evolution poses challenges, requiring versioning, migrations, and backward-compatible changes to minimize disruption.