A candle loses nothing by lighting up another candle.

Data Representation External Sorting Basics 2-Way Merge-sort (Requires 3 Buffers) If we have more main memory… Example: External Merge-Sort Pass 0 (Sorting) Pass 1/k (Merging) Cost of External Merge Sort Example ... Read More

Table of Contents Table of Contents ER Model Basic Stuff Entities and Attributes Relationships Subclasses Subclasses in ER Diagrams Constraints Modeling Constraints Why Constraints are Important? K... Read More

Constraints Kinds of Constraints Keys Primary Key vs Unique Foreign Keys Express Foreign Key with Attribute Express Foreign Key as Element Express Foreign Key with Unique Attributes Enforcing Foreign Key Constraints Dealing wit... Read More

Table of Content Relational Algebra Basic SQL Clauses More SQL Clauses LIKE AND, OR, NOT Multi-Relation Queries (Joins) Cartesian product (JOIN or INNER JOIN or CROSS JOIN) Theta/Equi Join (JOIN … ON … or NATURAL JOIN) LEFT/RIGHT JOIN FULL OUTER JOIN in MySQL Relation as ... Read More

Figure 1: Walmart Search Demo [PNG] Check out demo here Scripts Where we stored the data Demo Check out demo here I’m using a new domain name from freenom that will support for an year. I deployed the website on AWS ec2. Scripts Where we stored the data We eventually used MongoDB. It’s worth mentioning that w... Read More

Figure 1: Home Page [PNG] Assignment 3 Project Report Visualization 1 - Email Content Word Cloud Visualization 2 - Attack type popularity and connectivity Visualization 3 - Multi-Line Chart of Date & Stock Visualization 4 - Calendar View of Fraudulent Emails Visualization 5 - Bubble Map of Fraudulent Em... Read More

Query execution is part of the query processor. The SQL query will be firstly compiled then be executed. A simple diagram shows clearly below. Figure 1: Components of Query Processor [PNG] This note is mainly on query execution. Table of Contents Table of Contents Cost Model Why? And Some Assumptions Cost parameters ... Read More

Hello world! This is my first blog using GitHub Pages. I worked on this website for almost a day and found out GitHub Pages is very easy to write code. Originally, I was going for a written test from Tencent at 4 a.m. (7 p.m. in Beijing), but I found there actually isn’t any. Nevertheless, I stayed up late until now, like 3:44 a.m., to finish w... Read More

Related work & background What is Lucene Why should you care about Lucene? Information Retrieval (IR) Inverted index Foundations Indexing Incremental Index Updates Codec API Searching Conclusion Evaluation References Today I’m presenting a Paper called Apache Lucene 4 from proceedings of the Sigia 2012 workshop... Read More