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Phantom ReadDB/RDB 2019. 9. 30. 13:11
1. Overview Database transactions are defined by the four properties known as ACID. The Isolation Level (I in ACID) allows you to trade off data integrity for performance. The weaker the isolation level, the more anomalies can occur, and in this article, we are going to describe the Phantom Read phenomenon. 2. Description 2.1 Phenomenon If a transaction makes a business decision based on a set o..
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ACIDDB/RDB 2019. 9. 30. 13:06
1. Overview Transactions are omnipresent in today’s enterprise systems, providing data integrity even in highly concurrent environments. So let’s get started by first defining the term and the context where you might usually employ it. A transaction is a collection of read/write operations succeeding only if all contained operations succeed. 2. Description 2.1 Components 2.1.1 Atomicity Atomicit..
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Transactional locking mechanism and Multi-version concurrency control(MVCC)DB/RDB 2019. 9. 30. 10:26
1. Overview 1.1 Data Concurrency and Consistency Data concurrency: Ensures that users can access data at the same time Data consistency: Ensures that each user sees a consistent view of the data, including visible changes made by the user's own transactions and committed transactions of other users 2. Multiversion Read Consistency (MVCC) 2.1 Oracle Multi-versioning is the ability to simultaneous..
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MongoDB vs CasandraDB/Nosql 2019. 9. 30. 09:31
1. Overview When it comes to NoSQL databases, MongoDB and Cassandra may seem similar but are quite different. Both have similar use cases but are not intended for transactional data (i.e., accounting systems) 2. Description 2.1 Comparison of Features Feature MongoDB Cassandra Development language C++ Java Storage Type BSON files(Document-based) Column(Wide-columns) Expressive object model Yes No..
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Difference between Extract, Transform and Load(ETL) and Enterprise Application Integration(EAI)Modeling/Architecture 2019. 9. 29. 18:03
1. Overview Although both Extract, Transform and Load(ETL) and Enterprise Application Integration(EAI) technologies seem surprisingly similar from an architectural view - where so-called adapters (or connectors) provide access to systems and data sources transformations take place to standardize proprietary formats, or routing capabilities are used to move packets of data - ETL and EAI serve fun..
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Categorizing Design PatternModeling/DesignPattern 2019. 9. 29. 17:32
1. Overview Design patterns are solutions to software design problems you find again and again in real-world application development. Patterns are about reusable designs and interactions of objects. The 23 Gang of Four (GoF) patterns are generally considered the foundation for all other patterns. They are categorized into three groups: Creational, Structural, and Behavioral 2. Description 2.1 Cr..
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Memcached vs. RedisDB/InMemory 2019. 9. 29. 13:54
1. Overview Both tools are powerful, fast, in-memory data stores that are useful as a cache. Both can help speed up your application by caching database results, HTML fragments, or anything else that might be expensive to generate. But Redis is more powerful, more popular, and better supported than Memcached. Memcached can only do a small fraction of the things Redis can do. Redis is better even..
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Buffer vs. cacheDB/InMemory 2019. 9. 29. 13:53
1. Overview The semantics of a "buffer" and a "cache" are not totally different. even so, there are fundamental differences in intent between the process of caching and the process of buffering. A cache is typically used to store frequently accessed data. The data in a cache changes over time but the cache itself may be permanent. Caches often have sophisticated designs that support random acces..