DB
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S3, Block storage, File storage, and Object storageDB/RDB 2020. 2. 24. 01:02
1. Overview 2. Object Storage 2.1 What is Object Storage The term object storage, or object-based storage, derives its name because it packages data and metadata into objects. Metadata is essentially data that describes other data, or in the case of object-based storage, is information about the files that are typically stored within an object. Objects are stored in a flat structure or address s..
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DDL, DML, DCL, and TCLDB/RDB 2020. 2. 23. 23:29
1. Overview 2. Description 2.1 Data Definition Language (DDL) DDL is the short name of Data Definition Language, which deals with database schemas and descriptions, of how the data should reside in the database. CREATE – to create a database and its objects like (table, index, views, stored procedure, function, and triggers) ALTER – alters the structure of the existing database DROP – delete obj..
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Clustered and Non clustered indexDB/RDB 2020. 2. 23. 23:00
1. Overview With a clustered index the rows are stored physically on the disk in the same order as the index. Therefore, there can be only one clustered index. With a non clustered index there is a second list that has pointers to the physical rows. You can have many non clustered indices, although each new index will increase the time it takes to write new records. It is generally faster to rea..
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MySQL ScalingDB/RDB 2020. 2. 23. 20:48
1. Overview By default, the MySQL can be scaled either using Vertical or Hybrid approaches but not fully Horizontal approach. 1.1 What is Scaling, Why and When to use In simple words, Scaling is making your database handle more traffic or load for reading and write queries 2. Master-Slave approach Generally, we tend to create a Master-Slave architecture and route all the write queries on the Mas..
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MongoDB TransactionsDB/Nosql 2020. 2. 23. 20:18
1. Overview With multi-document ACID transactions in MongoDB, you get the only database that fully combines the power of the document model and a distributed systems architecture with ACID guarantees. Through snapshot isolation, transactions provide a consistent view of data and enforce all-or-nothing execution to maintain data integrity, even across sharded clusters. 2. Description Now for a tr..
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Dirty ReadDB/RDB 2019. 9. 30. 13:14
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 Dirty Read phenomenon. 2. Description 2.1 Phenomenon As previously mentioned, all database changes are applied to ..
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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..