What is the rounded result?

Two-Dimensional Interval Packing Challenge

Packing intervals is a classic SQL task that involves packing groups of intersecting intervals to their respective continuous intervals. In mathematics, an interval is the subset of all values of a given type, e.g., integer numbers, between some low value and some high value.

Eager Aggregation in SQL queries

Aggregation is a widely used way to summarize the content of a database. It is usually expressed with GROUP BY clause or just using aggregate functions (like COUNT or SUM). When the database engine executes a query with aggregations, it produces individual rows need to compute the required output and then performs the aggregation as (almost) last step. We discuss in this article how to re-write a query manually so that the order of operations will be different and when it can be beneficial.

Counting more efficiently

Nearly a decade ago, I wrote a post called “Bad habits : Counting rows the hard way.” In that post, I talked about how we can use SQL Server’s metadata to instantly retrieve the row count for a table.

Dijkstra's Algorithm

Introduction This article celebrates a classic algorithm [1] of Dijkstra (1930 – 2002) which finds a path of minimal cost between any pair of nodes in an undirected graph. His procedure is widely recognized as a fundamental tool for examining communication and transportation networks (eg. Google Maps) and is surprisingly simple. By his own admission, […]

Default Statistics Sampling

The First Place Seeing the New Year

The FK Columns

Parameter Defaults

Statistics Sampling Options