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Articles by Mithlesh Upadhyay
Page 4 of 4
MOSS Concurrency Control Protocol (Distributed Locking in Database)
The MOSS (Multi-Object Synchronized Scheduling) Concurrency Control Protocol manages concurrency in distributed database systems by handling hierarchical transactions with parent-child relationships and lock inheritance. Distributed Locking Types Optimistic locking − No locks acquired upfront; conflicts detected at commit time. Pessimistic locking − Locks acquired before accessing shared resources; conflicts prevented from the start. MOSS Protocol MOSS is a hierarchical locking protocol for nested transactions where subtransactions can inherit locks from ancestors ? ...
Read MoreModeling of UNION Types Using Categories
In DBMS, superclass/subclass relationships typically involve a single superclass. However, a union type or category represents a subclass that is a subset of the UNION of multiple distinct superclass entity types. Example: Vehicle Owner Category Consider a motor vehicle registration database with three entity types: PERSON, BANK, and COMPANY. A vehicle owner can be any one of these. We create a category called OWNER that represents the union of all three ? PERSON BANK COMPANY ...
Read MoreModel Planning for Data Analytics
Model planning is the process of selecting the right analytical models and techniques to analyze data effectively. It is a critical step in data analytics that ensures accurate, actionable insights for business decisions. Data Analytics Process Collection Raw sources Preparation Clean, validate Modeling Select model ...
Read MoreMethodologies of Large Scale Distributed Systems
Large-scale distributed systems handle massive data volumes, many concurrent users, and demanding performance requirements. Building them requires methodologies that help developers efficiently manage complexity, scalability, and fault tolerance. Companies like Google, Amazon, and Facebook use these systems extensively. Architecture of Distributed Systems Distributed systems consist of multiple nodes connected via a network, each running part of the distributed software. Understanding domain requirements, security, compliance, and future integrations is critical from the start. Node 1 Node 2 Node 3 ...
Read MoreMultiple Relation Queries and JOIN Ordering
Multiple relation queries involve joining several tables to produce a result set. The order in which JOIN operations are executed can significantly affect query performance. Query optimization determines the most efficient execution plan by evaluating different JOIN orderings. Challenges The query optimizer must determine the most efficient execution plan considering join selectivity, data size, distribution, and available access paths. With n tables, there are n! possible join orderings, making optimal selection a complex process. Table A 1M rows Table B ...
Read MoreMultiversion Concurrency Control Techniques
This article has a truncated Drawbacks section at the end. Let me fix that and clean up the SVGs: It is essential to maintain data consistency and prevent concurrency issues in database systems when multiple transactions access the same data simultaneously. Multiversion Concurrency Control (MVCC) techniques provide an efficient way to achieve this by maintaining multiple versions of data items. Concurrency Control Protocols Database systems provide concurrency control to ensure isolation among transactions, maintain consistency, and resolve conflicts arising from read−write and write−read operations. The main techniques used are − Two−phase locking protocol Timestamp ordering ...
Read MoreObject Identity, and Objects versus Literals
DBMS supports object-oriented data. It ensures direct correspondence between real-world objects and their representations in the database. This correspondence ensures that objects retain their integrity and identity. It enables easy identification and manipulation. Object Data Management System (ODMS) assigns unique identity to each independent object stored in the database. This unique identity is implemented through a system-generated object identifier (OID). This OID serves as distinct value assigned to each object by the system. It is not visible to external users. However it is internally utilized by the system to ensure the unique identification of each object and to establish and ...
Read MoreOffset-Fetch in MS SQL Server
Offset-Fetch is feature in MS SQL Server. It helps to retrieve subset of rows from result set. It consists of two components: OFFSET and FETCH. The OFFSET clause specifies the number of rows to skip from the beginning of the result set. FETCH clause determines the number of rows to retrieve. Syntax SELECT column1, column2, ... FROM table ORDER BY column OFFSET {integer_value} {ROWS | ROWS ONLY} FETCH {FIRST | NEXT} {integer_value} {ROWS | ROWS ONLY} ONLY; Explanation of Syntax SELECT column1, column2, ...: Specifies the columns to be selected from the table. FROM table Specifies the table from ...
Read MoreOLAP Guidelines (Codd_s Rule)
OLAP (Online Analytical Processing) is data processing technique. It is used to query and analyze data. It analyze data in real time from multiple sources. In 1993, EF Codd introduced 12 rules for the relational database model for OLAP systems. These rules are known as "Codd’s rules". These rules serve as a guideline for the design and development of OLAP systems. In this article, we will explore these 12 rules developed by Codd. Codd’s rules These are 12 rules for OLAP systems, as proposed by E.F. Codd − Multidimensional Conceptual View OLAP system should provide multidimensional conceptual view of ...
Read MoreOther Primary File Organizations
Files of Mixed Records In DBMS, file organizations are designed to handle records of a single type. However, in most real-world applications, multiple types of entities are interconnected in various ways. To represent relationships among records in different files, fields are connected. For example, a STUDENT record may have a connecting field Major_dept, whose value gives the name of the DEPARTMENT in which the student is majoring. The Major_dept field refers to a DEPARTMENT entity, which should be represented by a record of its own in the DEPARTMENT file. Retrieving field values from two related records requires retrieving one of ...
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