FAQ What is polyglot persistence principle? Polyglot Persistence is a term coined by Martin Fowler and Pramod Sadalage to describe the concept of using different data storage technologies to handle varying data storage needs within a given application. The principle behind polyglot persistence is that no single database can serve all needs of a modern application. Different kinds of data are best dealt with different types of databases. For example, you might use a relational database such as MySQL for transaction data, a NoSQL document store like MongoDB for semi-structured data, and a graph database like Neo4j for relationships between entities. Instead of trying to make one data storage technology work for all types of data, you use the type of database that is best suited for each particular need. This approach can result in a system that’s more scalable, performant, and easier to work with. Polyglot Persistence represents a shift away from the traditional, one-size-fits-all database strategy, allowing for a more flexible and optimized approach to data management. ...

Non-Repeatable Read A non-repeatable read occurs, when during the course of a transaction, a row is retrieved twice and the values within the row differ between reads. Phantom Read A phantom read occurs when, in the course of a transaction, two identical queries are executed, and the collection of rows returned by the second query is different from the first. Read Skew Read skew is that with two different queries, a transaction reads inconsistent data because between the 1st and 2nd queries, other transactions insert, update or delete data and commit. Finally, an inconsistent result is produced by the inconsistent data. ...

Designing a TPS for clouds will meet these challenges: Diverse functionality. The concept of translytics as “a unified and integrated data platform that supports multi-workloads such as transactional, operational, and analytical simultaneously in realtime, … and ensures full transactional integrity and data consistency”. Scale Cloud-first data platforms are designed to scale well beyond the limits of a single application. Latency With the thrust into new interactive domains like social networks, messaging and algorithmic trading,latency becomes essential. Multi-tenancy Maintaining access rights is therefore an important design consideration for TPSs. 论文的工作集中于以下几点： ...

An entirely re-designed version of Omid1. Omid’s job is to manage the transaction control plane. The transaction metadata includes: A dedicated table(Commit Tabla, CT) holds a single record per committing transaction. Per-row metadata for items accessed by transactions. Feature: A middleware oriented. Snapshot isolate should provide: Visibility check rules. Write conflicts detection. Visibility Check Rules Intuitively, with SI, a transaction’s reads all appear to occur the time when it begins($ts_r$) while its writes appear to execute when it commits($ts_c$). ...

Explore Rust Chapter 3 Types Arrays 不支持动态开数组： // an array of 100 int32 elements, all set to 1 let mut arr1 = [1;100]; // correct let n = 100; let mur arr2 = [1;c]; // error Vectors let mut arr = vec![0,6,4,8,1]; arr.sort() // increasing order arr.sort_by(|a,b| b.cmp(a)) // decreasing order If you know the number of elements a vector will need in advance, instead of Vec::new you can call Vec::with_capacity to create a vector with a buffer large enough to hold them all, right from the start. ...