How update works in transactional replication?

In a post about how update works I showed what happened when run an update with the same values. SQL Server is smart enough to see that and not changing anything and register minimum log. Another day I saw a comment to avoid updating records when none of the values are changing. Avoid updating records when … Continue reading How update works in transactional replication?

Database migration methods

When thinking about migration the most common issue is downtime. There are some methods that require downtime like backup/restore or less downtime using Log Shipping. You can choose several different methods to migrate your database.  For example, methods that require downtime include: Backup the database, manually copy the backup file to the machine and then … Continue reading Database migration methods

What is Stretch Database?

Stretch Database is a feature of SQL Server where data can be split between on-premises storage and cloud storage. With Stretch Database, cold, historical data is kept in the cloud and active data is kept on-premises for maximum performance. Stretch Database requires no changes to client applications or existing Transact-SQL queries, so you can implement … Continue reading What is Stretch Database?

Moving the msdb, model, and tempdb databases files

All system databases, except the resource database, can be moved to new locations to help balance I/O load. To move the msdb, model, and tempdb databases, perform the following steps: For each file to be moved, execute the ALTER DATABASE … MODIFY FILE statement. Stop the instance of SQL Server. Move the files to the … Continue reading Moving the msdb, model, and tempdb databases files

How SQL Server stores data?

SQL Server stores data in heaps or b-tree structures. Heaps are unordered set and balanced trees are ordered by their keys. Heaps and b-tree use collection of pages within the structure and it's called allocation units. IN_ROW_DATA -> contains all data. LOB_DATA -> structure for large objects used to stored in xml, varchar(max), nvarchar(max), varbinary(max) … Continue reading How SQL Server stores data?

Memory-optimized Logging

In a previous post I talked about transaction log works, and what about using a memory-optimized table? SQL Server has the feature Memory-Optimized Objects to improve performance. In-memory nonclustered indexes are implemented using a data structure called a Bw-Tree. A Bw-Tree is a lock and latch-free variation of a B-Tree. In-memory architecture: To enable an … Continue reading Memory-optimized Logging

Data types

Data types and Precedence of convert types SQL Server associates columns, expressions, variables, and parameters with data types. Data types determine what kind of data can be stored in the field: Integers, characters, dates, money, binary strings, etc. SQL Server supplies several built-in data types but you can also define custom types Built-in data types … Continue reading Data types