When.com Web Search

Search results

  1. Results From The WOW.Com Content Network
  2. Consistency (database systems) - Wikipedia

    en.wikipedia.org/wiki/Consistency_(database_systems)

    In database systems, consistency (or correctness) refers to the requirement that any given database transaction must change affected data only in allowed ways. Any data written to the database must be valid according to all defined rules, including constraints , cascades , triggers , and any combination thereof.

  3. ACID - Wikipedia

    en.wikipedia.org/wiki/ACID

    Consistency ensures that a transaction can only bring the database from one consistent state to another, preserving database invariants: any data written to the database must be valid according to all defined rules, including constraints, cascades, triggers, and any combination thereof. This prevents database corruption by an illegal transaction.

  4. Data consistency - Wikipedia

    en.wikipedia.org/wiki/Data_consistency

    The importance of point-in-time consistency can be illustrated with what would happen if a backup were made without it. Assume Wikipedia's database is a huge file, which has an important index located 20% of the way through, and saves article data at the 75% mark. Consider a scenario where an editor comes and creates a new article at the same time a backup is being performed, which is being ...

  5. Consistency model - Wikipedia

    en.wikipedia.org/wiki/Consistency_model

    Consistency models are used in distributed systems like distributed shared memory systems or distributed data stores (such as filesystems, databases, optimistic replication systems or web caching). Consistency is different from coherence, which occurs in systems that are cached or cache-less, and is consistency of data with respect to all ...

  6. Database transaction - Wikipedia

    en.wikipedia.org/wiki/Database_transaction

    In a database system, a transaction might consist of one or more data-manipulation statements and queries, each reading and/or writing information in the database. Users of database systems consider consistency and integrity of data as highly important. A simple transaction is usually issued to the database system in a language like SQL wrapped ...

  7. Data integrity - Wikipedia

    en.wikipedia.org/wiki/Data_integrity

    Data integrity is the maintenance of, and the assurance of, data accuracy and consistency over its entire life-cycle. [1] It is a critical aspect to the design, implementation, and usage of any system that stores, processes, or retrieves data.

  8. Relational model - Wikipedia

    en.wikipedia.org/wiki/Relational_model

    A database may define arbitrary boolean expressions as constraints. If all constraints evaluate as true, the database is consistent; otherwise, it is inconsistent. If a change to a database's relvars would leave the database in an inconsistent state, that change is illegal and must not succeed. [7]: 91

  9. Durability (database systems) - Wikipedia

    en.wikipedia.org/wiki/Durability_(database_systems)

    Existing database systems use volatile storage (i.e. the main memory of the system) for different purposes: some store their whole state and data in it, even without any durability guarantee; others keep the state and the data, or part of them, in memory, but also use the non-volatile storage for data; other systems only keep the state in main ...