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DynamoDB handles this using a service it calls the "log propagator", which subscribes to the replication logs in each node and sends additional Put, Update, and Delete requests to indices as necessary. [30] Because indices result in substantial performance hits for write requests, DynamoDB allows a user at most five of them on any given table. [31]
Amazon DynamoDB (launched January 2012) is quite different from the early (Amazon internal) Dynamo which was considered for the PACELC paper. [6] DynamoDB follows a strong leader model, where every write is strictly serialized (and conditional writes carry no penalty) and supports read-after-write consistency.
Consistent read was a new feature that was released at the same time as conditional put and conditional delete. As the name suggests, consistent read addresses problems that arise due to SimpleDB's eventual consistency model (See the Limitations section). Consider the following sequence of operations: Program A stores some data in SimpleDB.
Dynamo is a set of techniques that together can form a highly available key-value structured storage system [1] or a distributed data store. [1] It has properties of both databases and distributed hash tables (DHTs).
DynamoDB uses conditional update as an implementation of OCC. [17] Kubernetes uses OCC when updating resources. [18] YugabyteDB is a cloud-native database that primarily uses OCC. [19] Firestore is a NoSQL database by Firebase that uses OCC in its transactions. Apache Iceberg uses OCC to update tables and run maintenance operations on them.
In computer science, particularly the field of databases, the Thomas write rule is a rule in timestamp-based concurrency control. It can be summarized as ignore outdated writes . It states that, if a more recent transaction has already written the value of an object, then a less recent transaction does not need to perform its write since the ...
Conditional move instructions write the contents of one register over another only if the predicate's value is true, whereas conditional select instructions choose which of two registers has its contents written to a third based on the predicate's value. A more generalized and capable form is full predication. Full predication has a set of ...
The origin server requires the request to be conditional. Intended to prevent the 'lost update' problem, where a client GETs a resource's state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict. [24] 429 Too Many Requests (RFC 6585)