SQL Server Foreign Key Locking

Introduction In this article, we are going to see how SQL Server Foreign Key constraints are locking the parent record when executing a child record UPDATE. This situation is specific to SQL Server and happens even when using the Read Committed Snapshot Isolation level.

High-Performance Java Persistence Newsletter, Issue 26

Introduction Welcome to a new issue of the High-Performance Java Persistence Newsletter in which we share articles, videos, workshops, and StackOverflow answers that are very relevant to any developer who interacts with a database system using Java.

Clustered Index

Introduction In this article, we are going to see what a Clustered Index is and why it’s very important to understand how tables are organized when using a relational database system.

SQL Server JDBC – Set sendStringParametersAsUnicode to false

Introduction In this article, I’m going to explain why you should always disable the sendStringParametersAsUnicode default JDBC Driver setting when using SQL Server.

High-Performance Java Persistence Newsletter, Issue 25

Introduction Welcome to a new issue of the High-Performance Java Persistence Newsletter in which we share articles, videos, workshops, and StackOverflow answers that are very relevant to any developer who interacts with a database system using Java.

SQL Server deadlock trace flags

Introduction In this article, I’m going to explain how you can find the cause of an SQL Server deadlock using trace flags and the SQL error log. As a rule of thumb, the more locks are acquired, the higher the probability of a deadlock. And, since SQL Server uses 2PL by default, it’s not uncommon to have to track deadlock issues that affect application performance.

Merge Join Algorithm

Introduction In this article, we are going to see how the Merge Join Algorithm, also known as Sort-Merge Join, works and when it’s suitable for a relational database system to employ it in order to execute an SQL JOIN query.

SQL Server OPENJSON – Map JSON to a relational table

Introduction In this article, I’m going to explain how the SQL Server OPENJSON function works and how it can help you transform a JSON object into a relational database table. When using a relational database system, it’s a very good idea to design the database schema according to the relational model. However, there are specific situations when the relational model is way too strict, and that’s when a JSON column type might be very handy. For instance, as I explained in this article, when designing an audit log table, it’s much more… Read More

Hash Join Algorithm

Introduction In this article, we are going to see how the Hash Join Algorithm works and when it’s suitable for a relational database system to employ it in order to execute an SQL JOIN query.

Nested Loop Join Algorithm

Introduction In this article, we are going to see how the Nested Loop Join Algorithm works and when it’s suitable for a relational database system to employ it in order to execute an SQL JOIN query.