Chunk is a control data (C/D) and packet set used in Stream Control Transmission Protocol (SCTP). SCTP packets are comprised of common headers and data chunks and vary by content. Data chunks are defined in RFC 4960, which updates RFC 2960 and RFC 3309.
A database guarantees the following four properties to ensure database reliability, as follows:
Atomicity: A database follows the all or nothing rule, i.e., the database considers all transaction operations as one whole unit or atom. Thus, when a database processes a transaction, it is either fully completed or not executed at all.
Consistency: Ensures that only valid data following all rules and constraints is written in the database. When a transaction results in invalid data, the database reverts to its previous state, which abides by all customary rules and constraints.
Isolation: Ensures that transactions are securely and independently processed at the same time without interference, but it does not ensure the order of transactions. For example, user A withdraws $100 and user B withdraws $250 from user Z’s account, which has a balance of $1000. Since both A and B draw from Z’s account, one of the users is required to wait until the other user transaction is completed, avoiding inconsistent data. If B is required to wait, then B must wait until A’s transaction is completed, and Z’s account balance changes to $900. Now, B can withdraw $250 from this $900 balance.
Durability: In the above example, user B may withdraw $100 only after user A’s transaction is completed and is updated in the database. If the system fails before A’s transaction is logged in the database, A cannot withdraw any money, and Z’s account returns to its previous consistent state.
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