Michael C. McKay

Understanding Surrogate Keys and Their Importance in Database Design

data integrity, database design, primary keys, referential integrity, unique identifier, unique identifiers

Understanding Surrogate Keys and Their Importance in Database Design

In the world of database management, keys play a crucial role in organizing and maintaining data. One such key is a surrogate key, which is a unique identifier assigned to each record in a table. Unlike primary keys, which are derived from the data itself, surrogate keys have no meaning or relation to the entity or attribute they represent. This makes them an invaluable tool in database design, as they provide a system-agnostic way of tracking and linking records.

Surrogate keys are especially useful in situations where primary keys based on natural data, such as names or addresses, can change or be duplicated. By using surrogate keys, database designers can ensure the integrity of their data, as each record will have a unique identifier regardless of any changes to the underlying values.

Furthermore, surrogate keys simplify the process of creating relationships between tables. Instead of relying on complex joins based on multiple attributes, surrogate keys provide a simple and efficient method for establishing referential integrity. Foreign keys can be used to link records across tables, creating a logical and normalized database structure.

In addition to their practical benefits, surrogate keys also offer performance advantages. Compared to composite keys or large natural keys, surrogate keys are typically shorter in length and easier to index. This can lead to faster querying and improved overall system performance, especially in large databases with millions of records.

What are Surrogate Keys

In the context of database design, surrogate keys are artificially created unique identifiers assigned to records in a table. They are not derived from any existing attribute or data in the table, but rather generated by the database management system.

Surrogate keys are often used to normalize a database and ensure data integrity. By providing a unique identifier for each entity or record in a table, surrogate keys simplify the management of relationships between tables. They act as a referential integrity constraint and can be used as indexes for efficient data retrieval.

Surrogate keys are different from natural or composite keys, which are derived from existing attributes in the data. They do not have any meaning or significance outside of their role as identifiers. Surrogate keys are typically simple, numeric values that are automatically generated by the system, such as an auto-incremented integer.

One of the main advantages of using surrogate keys is that they are not affected by changes in the underlying data attributes. This means that even if an attribute value changes, the surrogate key remains the same, ensuring the integrity of relationships between tables.

In summary, surrogate keys are unique identifiers created by the database management system to simplify data management, ensure data integrity, and facilitate relationships between tables. They play a crucial role in the design and normalization of databases, providing a consistent and reliable means of identifying and referencing records.

Definition of Surrogate Keys

A surrogate key is a unique identifier that is introduced in a database to simplify and improve data management. It is a generated key that has no meaning or relation to the data it represents. Surrogate keys are often used in database design to replace or supplement natural keys, which are identifiers derived from data attributes that have inherent meaning. Surrogate keys are most commonly used as primary keys, but they can also be used as foreign keys to establish relationships between tables.

One of the main advantages of surrogate keys is their ability to simplify data normalization. By using a surrogate key as the primary key of a table, the designer can remove the need to have complex composite keys that include multiple attributes. This helps to reduce data redundancy and improves the overall structure and organization of the database.

In addition to simplifying data normalization, surrogate keys also play a crucial role in maintaining data integrity and ensuring referential integrity in a database. Because surrogate keys are generated by the system, they are guaranteed to be unique within their respective tables. This uniqueness allows for more accurate and efficient data searching and indexing, as well as better control over data manipulation and updates.

Surrogate keys are particularly useful in situations where the natural keys of an entity may change or where there is no suitable natural key available. For example, in a customer database, a surrogate key could be used as the primary key instead of a customer’s social security number, which may change over time. This ensures that the primary key remains stable and enables easier maintenance and retrieval of customer records.

In summary, surrogate keys are generated unique identifiers that are used as primary or foreign keys in a database. They provide a simplified and efficient way to manage data, improve data integrity, and establish relationships between entities. By decoupling the key from the data attributes, surrogate keys help to normalize the database and ensure accurate and reliable data management.

Examples of Surrogate Keys

Surrogate keys are unique identifiers that are introduced by the database management system to serve as the primary key for a table. They are not derived from any attribute or combination of attributes of the entity being represented but are instead generated by the system. These surrogate keys are widely used in database design to ensure referential integrity and simplify data management.

Some examples of surrogate keys include:

  1. Sequential Number: One common type of surrogate key is a simple sequential number assigned to each record in a table. This is often used in tables that do not have an obvious candidate key or when the primary key needs to be hidden from users.
  2. UUID: Another type of surrogate key is a universally unique identifier (UUID), which is a 128-bit value that is globally unique across all tables and databases. UUIDs are generated using algorithms that guarantee their uniqueness even in distributed systems.
  3. Hash Value: Surrogate keys can also be generated using hash functions, which take an attribute or combination of attributes and produce a unique value that can be used as the primary key. Hash values are commonly used in indexing and searching operations.
  4. Auto-Incrementing Integer: In many databases, an auto-incrementing integer is used as a surrogate key. This is a numeric value that automatically increments for each new record added to the table.

Regardless of the specific type of surrogate key used, their main purpose is to provide a unique identifier for each record in a table. They simplify the management of relationships between tables by establishing clear and unambiguous associations through foreign key constraints. Surrogate keys also promote database normalization by reducing redundancy and improving efficiency in data access and retrieval operations.

Use of Surrogate Keys in Database Design

Use of Surrogate Keys in Database Design

In database design, a surrogate key is an additional attribute that is assigned to a primary key of an entity or table. It is a unique identifier that is used to uniquely identify records in a database and simplify data management.

Surrogate keys are important in database design for several reasons. First, they provide a simple and efficient way to identify records in a table. Unlike natural keys, which are based on attributes of the entity itself, surrogate keys are system-generated and have no meaning outside of the database. This makes them ideal for use as primary keys as they do not change when the data changes.

Another important use of surrogate keys is in maintaining referential integrity in database relationships. When two entities are related through a foreign key relationship, the foreign key attribute in the child table must match a primary key in the parent table. Surrogate keys make this process easier, as they provide a stable and reliable identifier for the records in the parent table.

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Surrogate keys also help to normalize the structure of a database. Normalization is the process of organizing data in a database to eliminate redundancy and improve efficiency. Surrogate keys can be used to simplify the structure of tables by replacing complex composite primary keys with a single attribute.

In addition, surrogate keys can be used to improve query performance by creating indexes on them. Indexes are data structures that allow for quicker retrieval of data based on specific attributes. By creating an index on a surrogate key, the database management system can quickly locate and retrieve the desired records.

In conclusion, the use of surrogate keys in database design is essential for maintaining data integrity, simplifying data management, and improving query performance. By providing a unique identifier for records, surrogate keys ensure that relationships between entities are properly maintained and that data can be efficiently retrieved and manipulated.

Importance of Surrogate Keys

Surrogate keys play a crucial role in maintaining the integrity of a database. They are unique identifiers that are generated systematically by the database management system (DBMS), and they provide a way to uniquely identify records in a table or entity.

One of the main reasons why surrogate keys are important is their ability to simplify the management of relationships between tables. Instead of using natural keys, which are attributes that are inherent to the data itself, surrogate keys provide a standardized and consistent approach to identifying entities. This allows for easier data normalization, as tables can be designed and connected based on the surrogate keys, rather than relying on complex and multi-attribute keys.

Surrogate keys also play a crucial role in enforcing referential integrity, which is the consistency and correctness of relationships between tables. By using surrogate keys as foreign keys in related tables, the DBMS can ensure that the relationships between the tables are valid and that no records are orphaned or incorrectly connected. This is achieved through the use of referential integrity constraints, which are rules that define the allowed relationships between tables based on their surrogate keys.

In addition to maintaining data integrity and simplifying database design, surrogate keys also have practical benefits in terms of performance and indexing. Since surrogate keys are systematically generated and do not have any inherent meaning, they can be efficiently indexed, allowing for faster search and retrieval of data. This is especially important in large databases with millions of records, where efficient indexing can greatly improve query performance and overall system responsiveness.

In conclusion, surrogate keys are an essential component of a well-designed database. They provide a unique identifier for each record, simplify relationships between tables, enforce referential integrity, and improve performance. By understanding the importance of surrogate keys and incorporating them into the database design, developers can ensure the integrity, efficiency, and overall effectiveness of their database systems.

Ensuring Uniqueness

In relational database design, ensuring uniqueness is a critical aspect to maintain data integrity. The primary way to ensure uniqueness is by using primary keys and unique constraints. A primary key is an attribute or a combination of attributes that uniquely identifies each record within a table. It serves as a reference point for other tables and helps establish relationships between entities. Additionally, primary keys can be used as foreign keys in other tables, providing a way to link related data.

When designing a database, it is important to normalize the data and eliminate any redundant information. Surrogate keys play a crucial role in this process. A surrogate key is a unique identifier that is generated by the system, often in the form of an auto-incrementing integer. These surrogate keys help simplify the management of primary keys and ensure uniqueness within a table.

Another method to ensure uniqueness is by creating indexes on specific attributes. An index is a data structure that allows for faster retrieval of data based on the indexed attribute. By creating indexes on attributes that need to be unique, such as email addresses or social security numbers, the database system can enforce the uniqueness constraint efficiently.

Furthermore, referential integrity can be enforced by using foreign keys. A foreign key is a field or a combination of fields in a table that refers to the primary key of another table. By creating relationships between tables using foreign keys, the database system can ensure that the values in the foreign key correspond to valid records in the referenced table.

In summary, ensuring uniqueness in a database is crucial for maintaining data integrity. Primary keys, unique constraints, surrogate keys, indexes, and referential integrity through foreign keys all play a role in this process. They help to establish relationships between tables, normalize the data, simplify management, and enforce constraints to ensure uniqueness and reliability in the database.

Improving Performance

When designing a database, one important consideration is to improve performance. This can be achieved by effectively using surrogate keys. Surrogate keys are unique identifiers that are generated by the database management system and are used to uniquely identify records in a table. Unlike primary keys, which are based on the actual data in a table, surrogate keys have no inherent meaning and are simply used as a means to uniquely identify records.

By utilizing surrogate keys, the database can improve performance in several ways. Firstly, surrogate keys can simplify the management of foreign key relationships. Instead of having to use a composite key or reference multiple attributes to establish relationships between tables, surrogate keys can be used as a single attribute to establish these relationships. This can simplify the design of the database schema and also improve query performance when joining tables.

In addition, the use of surrogate keys can also improve database indexing. Indexes are used to optimize query performance by creating a separate data structure that allows for faster access to data. By using a surrogate key as the primary key of a table, the database management system can create a clustered index, which physically organizes the data based on the surrogate key values. This can improve the performance of queries that involve searching, sorting, and joining tables.

Another advantage of using surrogate keys is that they can help to ensure data integrity. Surrogate keys are typically created using an auto-incrementing sequence or a randomly generated value, which ensures their uniqueness. This avoids the potential issues that can arise from using business-related attributes as primary keys, such as the need for frequent updates due to changes in the attribute values. By using surrogate keys, the integrity of the data is maintained, as the surrogate key values remain constant regardless of any changes to the underlying attributes.

In conclusion, the use of surrogate keys can play a crucial role in improving performance in database design. They simplify the management of foreign key relationships, improve database indexing, and ensure data integrity. By effectively utilizing surrogate keys, database designers can optimize query performance and create a more efficient and normalized database structure.

Flexibility in Database Design

Flexibility in Database Design

Flexibility is an important aspect of database design as it allows for efficient and effective management of data. One way to achieve flexibility is through the use of surrogate keys. Surrogate keys are unique identifiers that are created by the system rather than being derived from the data itself. These surrogate keys can be used as primary keys for tables, providing a reliable and easily manageable index for the database.

Surrogate keys offer flexibility in database design by allowing for easy manipulation of data. They are not affected by changes or updates to the data, ensuring that the relationships between tables remain intact. With surrogate keys, it is possible to create and modify relationships between entities without the need to adjust primary keys or other data attributes, simplifying the process of database management.

Another benefit of using surrogate keys is that they can help ensure data integrity. Surrogate keys, along with proper referential constraint management, provide a way to enforce data integrity rules in the database. This means that the relationships between tables are maintained and that data is consistent and accurate, reducing the likelihood of errors or inconsistencies in the data.

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In addition, the use of surrogate keys can simplify the process of database normalization. Database normalization is a technique used to organize data in tables to minimize redundancy and improve efficiency. Surrogate keys can be used as unique identifiers for entities, reducing the need to include additional attributes in tables and improving the overall structure and performance of the database.

In conclusion, flexibility in database design is essential for efficient data management. Surrogate keys provide a way to achieve this flexibility by offering a reliable and easily manageable index for the database. They allow for easy manipulation of data, ensure data integrity, and simplify the process of database normalization. By incorporating surrogate keys into the design, database systems can be more flexible and adaptable to changing data requirements.

Implementing Surrogate Keys

When designing a database, one important consideration is how to identify and uniquely distinguish records within a table. Surrogate keys play a vital role in this process by providing a normalized, unique identifier for each entity or record.

A surrogate key is an artificial identifier assigned to a record that has no inherent meaning or data associated with it. Instead, it serves as a primary key, allowing for efficient data management. This is particularly useful in cases where the natural keys, such as a combination of attributes, may change or become ambiguous.

To implement surrogate keys, a unique constraint is typically defined on the surrogate key attribute of the table. This ensures that each value within the attribute is unique, preventing duplicates and maintaining data integrity. Additionally, referential integrity can be enforced by using foreign keys, which establish relationships between entities or tables based on the surrogate key.

Surrogate keys are especially valuable in situations where an entity has multiple relationships with other entities. By using a surrogate key, the relationships can be easily managed and maintained, simplifying operations such as joins and updates. This also allows for faster querying and indexing, as the surrogate key is typically shorter and more efficient compared to a composite key.

When implementing surrogate keys, it is important to understand their purpose and use them appropriately. They should be used in conjunction with the natural keys and not as a replacement. A well-designed database should utilize both types of keys to ensure data integrity and accurate retrieval of information.

Choosing the Right Surrogate Key

The selection of the right surrogate key is crucial for ensuring the efficiency and integrity of a database system. Surrogate keys are system-generated unique identifiers assigned to a record that do not have any inherent meaning or relationship to the data they represent. When choosing a surrogate key, it is important to consider factors such as data uniqueness, performance, and scalability.

One of the primary benefits of using surrogate keys is maintaining data integrity. Surrogate keys eliminate the risk of data duplication or ambiguity that can occur when using natural keys. They provide a reliable method for uniquely identifying each entity in the database, ensuring that there are no conflicts or inconsistencies in the data.

Surrogate keys also simplify the management of relationships between tables. With surrogate keys, foreign key relationships can be established easily and efficiently. This simplification is especially important when dealing with complex databases with multiple tables and intricate relationships.

Another factor to consider when choosing a surrogate key is performance. Surrogate keys can improve the performance of database operations, such as searching, sorting, and indexing. Since surrogate keys are typically numeric and have a fixed length, they create a more efficient index structure compared to natural keys, which may be longer or involve string comparisons.

The scalability of the database system should also be taken into account when selecting a surrogate key. Surrogate keys allow for greater flexibility and ease of maintenance when adding or modifying records. They eliminate the need to update existing records or modify existing primary keys, which can be a cumbersome and time-consuming process, especially in large databases.

In conclusion, choosing the right surrogate key is essential for database design. By considering factors such as data integrity, performance, and scalability, a appropriate surrogate key can be selected that will optimize the management of relationships and improve the overall efficiency of the database system.

Generating Surrogate Keys

In the context of database design, surrogate keys are often used to generate unique identifiers for entities. Surrogate keys are artificial identifiers that are not derived from any attribute or set of attributes within the entity. They are used in place of natural keys, which can be problematic when dealing with complex referential relationships.

The generation of surrogate keys is an important aspect of database management. One common approach is to use an auto-incrementing integer value as the surrogate key. This value is automatically generated by the system and ensures uniqueness within the table. Another approach is to use a globally unique identifier (GUID), which is a random string of alphanumeric characters that is highly unlikely to clash with any other key in the system.

Surrogate keys provide a number of benefits in database design. Firstly, they simplify the management of relationships between entities. By using a surrogate key as a foreign key in a related table, the referential integrity and data consistency can be maintained easily. Additionally, using surrogate keys allows for easier modification of the primary key of an entity if needed, as the relationships do not need to be updated. Surrogate keys also help to enhance performance by providing a smaller target for indexing and making it easier to create unique index constraints.

In summary, surrogate keys play a crucial role in database design by providing unique identifiers for entities, simplifying the management of relationships, ensuring referential integrity, and enhancing performance. The generation of surrogate keys can be done using auto-incrementing integer values or globally unique identifiers, depending on the specific requirements of the system. By utilizing surrogate keys, database designers can normalize the data and ensure efficient and effective data management.

Automatic vs Manual Generation

Surrogate keys are unique identifiers that are generated by a system or an application automatically, without any input from the user. These keys are typically used in database design to uniquely identify records in a table and establish relationships between different entities.

Automatic generation of surrogate keys has several advantages. Firstly, it eliminates the need for manual intervention, reducing the chances of errors and inconsistencies in the data. The keys are generated by the system in a consistent and predictable manner, ensuring that each record has a unique identifier. This simplifies the management of the database and improves the efficiency of data retrieval, as indexes can be created on the keys to enhance query performance.

On the other hand, manual generation of surrogate keys involves assigning unique identifiers to records by hand. This approach can be useful in certain cases, such as when the natural attributes of an entity cannot serve as a primary key. However, it requires careful planning and coordination to ensure that the assigned keys are unique and do not violate any referential integrity constraints.

Manual generation of surrogate keys can also complicate database normalization. When using natural keys, which are based on attributes that naturally exist in the entity being represented, the process of normalizing the database becomes simpler. However, manual surrogate keys introduce an additional attribute to each table, which can increase redundancy and complexity.

In conclusion, the choice between automatic and manual generation of surrogate keys depends on the specific requirements of the database and the entities being represented. Automatic generation provides consistency, efficiency, and simplicity, while manual generation offers flexibility and control. Database designers need to carefully consider these factors when deciding on the appropriate approach for their system.

Best Practices for Using Surrogate Keys

Surrogate keys are artificial identifiers that are generated by the system and used as primary keys in database tables. They play a crucial role in database design and management by providing a unique identifier for each record in a table. Here are some best practices for using surrogate keys:

  1. Use surrogate keys as primary keys: Surrogate keys should be used as primary keys for all tables in order to ensure uniqueness and maintain data integrity. This helps to avoid any potential issues related to the management of natural keys and their inherent dependencies.
  2. Assign surrogate keys automatically: Surrogate keys should be generated automatically by the system using a predefined algorithm or mechanism. This eliminates the need for manual assignment and reduces the chances of human error.
  3. Normalize data using surrogate keys: Surrogate keys facilitate data normalization by providing a consistent and standardized way of referencing entities and establishing relationships between tables. This improves data organization and reduces redundancy.
  4. Utilize surrogate keys in relationships: Surrogate keys are useful in establishing referential integrity between tables. They enable the creation of foreign key relationships, which help to maintain the consistency and accuracy of data across different tables.
  5. Create indexes on surrogate keys: Surrogate keys should be indexed in order to improve query performance and optimize data retrieval. This allows for efficient searching, sorting, and joining of records based on their surrogate key values.
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By following these best practices, you can effectively utilize surrogate keys in your database design. They provide a reliable and manageable way to uniquely identify records and ensure the integrity of your data.

Avoiding Duplicate Surrogate Keys

Surrogate keys are unique identifiers that are added to database tables to ensure consistency and integrity of the data. They are often used in place of natural keys, which may not be unique or may change over time. However, it is important to avoid duplicate surrogate keys in order to maintain the integrity of the database.

To avoid duplicate surrogate keys, it is important to properly design and manage the surrogate key system. One way to do this is to normalize the data, which involves breaking down the data into smaller, atomic units to eliminate redundancy. By ensuring that each record has a unique combination of attributes, the likelihood of generating duplicate surrogate keys is reduced.

Another way to prevent duplicate surrogate keys is to use referential integrity constraints in the database management system. These constraints define relationships between entities and can prevent the creation of duplicate keys through the use of foreign key constraints. By specifying that a foreign key must reference a unique key in another table, the system will prevent the creation of duplicate keys.

In addition to using referential integrity constraints, it is also important to create an index on the surrogate key attribute. This can help improve the performance of queries that involve searching for or joining records based on the surrogate key. By creating an index on the surrogate key, the system can quickly locate and retrieve the desired records.

In summary, avoiding duplicate surrogate keys is crucial for maintaining the integrity of a database. By normalizing the data, using referential integrity constraints, and creating an index on the surrogate key attribute, the likelihood of generating duplicate keys can be minimized. This ensures that each record in the database has a unique identifier and allows for efficient retrieval and management of the data.

Ensuring Consistency in Surrogate Key Usage

When designing a database, it is important to ensure consistency in the usage of surrogate keys. Surrogate keys are artificially generated unique identifiers that are used in database tables to ensure data integrity and manage relationships between records.

One way to ensure consistency is by defining a constraint on the surrogate key attribute. A constraint can be set to enforce the uniqueness of the surrogate key values, preventing any duplicates from being entered into the database. This constraint can be defined as a PRIMARY KEY or a UNIQUE constraint.

Another important aspect of ensuring consistency in surrogate key usage is to normalize the database. Normalization is the process of organizing data into tables in order to eliminate redundancy and improve data integrity. By normalizing the database, surrogate keys can be used as primary keys in each table, ensuring that each record has a unique identifier.

In addition to normalization and constraints, it is also important to maintain referential integrity in the use of surrogate keys. Referential integrity ensures that relationships between tables are properly managed, preventing any orphaned records. This can be achieved by using foreign keys, which are attributes in a child table that reference the surrogate key in the parent table.

Consistency in surrogate key usage is crucial for the effective management of data in a database. It ensures that each record has a unique identifier, allows for proper relationships between tables, and maintains data integrity. By properly defining constraints, normalizing the database, and enforcing referential integrity, the usage of surrogate keys can be consistent and reliable.

Documenting Surrogate Key Usage

Surrogate keys play a crucial role in database design as they provide a unique identifier for each entity in a database. They are artificially created and do not have any inherent meaning. In order to understand the usage of surrogate keys, it is important to document their implementation and usage in the database.

When documenting surrogate keys, it is essential to specify the entity or table for which the surrogate key is being used. This helps in understanding the purpose of the surrogate key and its relationship with other entities in the database. Additionally, the documentation should include the primary keys of the related tables, as surrogate keys are often used as foreign keys to establish relationships.

In terms of data integrity, documenting surrogate keys helps in ensuring that the keys are used consistently across the database. It serves as a reference point for maintaining referential integrity and avoiding data duplication. By clearly documenting the surrogate key usage, database administrators can enforce data management rules and constraints to maintain the accuracy and reliability of the database.

Furthermore, documenting surrogate key usage can aid in database normalization. Surrogate keys simplify the process of establishing relationships between tables, as they can be used to uniquely identify records. They are particularly useful when dealing with composite keys or when the natural keys of entities are subject to change.

Documenting the usage of surrogate keys can also help in performance optimization. By creating an index on the surrogate key, it becomes easier to search and retrieve records from the database. This can greatly enhance the efficiency of queries and improve the overall performance of the system.

In summary, documenting surrogate key usage is essential for maintaining the integrity and efficiency of a database. It provides a clear understanding of how surrogate keys are utilized in the database, their relationships with other entities, and their impact on data management and performance optimization.

FAQ about topic “Understanding Surrogate Keys and Their Importance in Database Design”

Why are surrogate keys important in database design?

Surrogate keys are important in database design because they provide a unique identifier for each record in a table, regardless of its natural attributes. This helps to ensure data integrity and simplifies the process of joining tables together.

What are the advantages of using surrogate keys?

Using surrogate keys has several advantages. Firstly, they eliminate the need to have composite keys, which can be cumbersome to work with. Secondly, they provide a stable identifier for a record, even if its natural attributes change. Lastly, surrogate keys can improve performance by reducing the size of join operations.

Can surrogate keys be used in all types of database relationships?

Yes, surrogate keys can be used in all types of database relationships. They can be used as the primary key in a table, or as a foreign key in a related table. Surrogate keys provide a consistent and unique identifier for records, regardless of the type of relationship.

Are surrogate keys always auto-generated?

No, surrogate keys are not always auto-generated. While auto-generated surrogate keys are commonly used, they can also be manually assigned. However, it is generally recommended to use auto-generated keys to ensure uniqueness and avoid human errors in key assignment.

What are some common scenarios where surrogate keys are used?

Surrogate keys are commonly used in scenarios where there is no suitable natural key for a table, or when the natural key may change over time. They are also used when there is a need to simplify join operations between tables, or when there is a requirement for a unique identifier that is independent of the data attributes in a table.

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