In this article, you’ll learn in-depth about the numerous complexities that comprise Microsoft SQL Server CDC (Change Data Capture) that spans its creation, a brief overview, and its functions.
The Launch of the Microsoft SQL Server CDC Feature
In the current business climate, where data is the essential tool for any company in the modern world, data security is a must. Change Data Capture feature assumes a vital role in ensuring data security and durability. It’s not just about ensuring that data is safe from hacker attacks or breaches but also about safeguarding changes to ensure that the values are recorded in a way that will not affect their history. There have been a variety of solutions in the past, such as triggers, timestamps, complex queries, and auditing of data but not with any satisfaction.
Microsoft’s first practical solution was made available in 2005 through the SQL Server CDC product. Its more advanced features include “after the update,” “after insert,” as well as “after delete” capabilities. But, the released version didn’t find much acclaim with administrators of databases who thought it to be too complex. In 2008, Microsoft introduced a more refined version of SQL Server CDC that became highly well-known. It allowed DBAs and developers to collect and archive historical changes and data without different processes.
An Outline of Microsoft SQL Server CDC
SQL Server CDC uses the SQL Server to make changes such as insert, update and insert, the details of which are accessible through a straightforward relational format. In the case of modified and altered rows, all the inputs required to capture changes to the ecosystem, such as metadata and information about columns, are readily available. The modifications made are recorded in tables that reflect the columns of the tables stored in the tracker—the table-valued functions required for the task control access to the change information.
The ETL (Extract Transform and load) application is among the finest examples of a customer targeted by the SQL Server CDC technology. The modified data in SQL source tables are slowly transferred using an ETL application to an information warehouse or data warehouse.
What does this SQL Server CDC score over other competitors? In general, the source tables of the data warehouse reflect all modifications made to them, but they need to be continually updated. This is a complicated and time-consuming process. However, it is a system that guarantees the smooth flow of information that is structured so that users can adapt it to different target platforms is better. This is exactly what SQL Server CDC does for companies.
The Working of Microsoft SQL Server CDC
Any changes made by the users in tables are monitored and tracked through Change Data Capture. The changes are then stored in relational tables, which offer an instant and seamless data retrieval using T-SQL. If CDC applies to a table in a database and a mirror image of the table being tracked is made. The columns in the tables that are replicated include additional metadata columns that indicate the changes that have been made to database rows.
Other than this one aspect, the source tables and replicated ones appear identical in every aspect. Once this SQL Server CDC activity is completed, the audit tables can be used to keep track of the log tables and keep track of the activities that took place.
The reason for the changes in CDC is recorded in the transaction logs of SQL Server CDC. When any change, such as an insert deletion, update, or insert, occurs in the source tables tracked, The details of the entries are recorded in the log, making it an essential component of CDC. The log, which contains all details of the changes, is later read, and the changes are then linked to the changes table portion of the table.
Forms of Change Data Capture
There are two types that makeup SQL Server CDC.
One is the log-based CDC. In this case, the transactions log and the database file are scrutinized by the system to learn the modifications made in the original database. All modifications made by the source database are replicated in the database that is being targeted. The primary benefit of this version of SQL Server CDC is that it is highly reliable, and there is the possibility of not being able to keep track of the changes made. Additionally, it has an extremely minimal impact on the database production system. Schemas of tables used for production are not required to be changed, and there is no requirement to create new tables. However, the drawback is that this technique works only on databases that can support log-based CDC.
The second type in SQL Server CDC is based on triggers stored in the database that will respond automatically when a change or event is observed, which reduces the costs of obtaining changes. However, it will increase the price of operating the base system since additional time must be spent every time the database needs to be refreshed.
There are a variety of advantages to the trigger-based SQL Server CDC. One of them is that it can be easily implemented. Information of the logs for every transaction is available inside the tables of shadows. Support can be directly available for selected databases through SQL API and, finally, SQL API. Lastly, changes are implemented more quickly. As the first form of CDC, There are a few disadvantages. There are issues with trigger overload, and triggers are disabled during operation. In addition, data performance can be negatively affected since this technique requires multiple writings to the database each when there is a change made to rows.
SQL Server CDC is an essential benefit for companies driven by data.