SQL Server Recovery Models-Simple, Full and Bulk Log

Introduction To Recovery Models

Three recovery models are offered by every version of SQL Server. These models are Simple, Bulk-Logged and full. Among these three models, commonly used models are simple and full. These models differ in the backup and recovery process and affect disk utilization and database performance if that is not properly configured. SQL Server backup and restore operations occur within the recovery model context. Basically, a recovery model is used to control transaction log maintenance.

It is a database property that can control the way in which transactions are logged and also to know whether the transaction log requires backup and the kind of restore operations available Moving ahead, we will discuss the three recovery models and the difference between simple and full recovery model you must know in 2020, while any database can be switched to another model at any time.

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What is the Simple Recovery Model?

In the case of the Simple recovery model, the database is just the same as the last backup. In this model, all the transactions like inserts, updates, deletions, and other database activities are committed immediately as and when they take place. In this model , the amount of disc space is required for storing database and it only gets large in the case when numerous transactions take place.  As there is no need to maintain the transaction history, so, as a result, the speed of execution increases of SQL database.

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Now, the query processing gets more time for execution and the task execution also gets faster rather than managing logs. However, there is only a single risk in this process that is catastrophic data loss. Usually, the success of the database depends upon its complete transaction management process.

What is the Full Recovery Model?

In the case of the full recovery model, the database is allowed to be restored at a point of time by using the transaction log information that helps to reach a point at any required time. Here we can take the example of a large database insertion or deletion operation, so in such a scenario, the database will be restored just before the action is performed at the database.

Here, the SQL Server is managed by more than one organization that  is involved in the transaction. In the case of the full recovery model, the transaction log remains small enough and database performance has been improved a lot as enough recoverable information is now available that can help in case of any database mishap.

How to Choose the Best Recovery Model?

Simple and full recovery models are mostly used by the organizations, but sometimes they can get stuck among both and may have to decide which model is best for them? So to test or for the development of a database simple recovery model is appropriate while for any production database requirement, the full recovery model can be suggested, as it can also be supported by a bulk-logged recovery model occasionally.

For a small production database, a simple recovery model can be suitable, especially when it is a read-only data warehouse model. In order to choose the best recovery model for any organization, there are two concepts that can help them,one is recovery goals and the other is a requirement for the database along with your capability to manage log backups.

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Recovery Goal and Requirement Identification

You should consider recovery goals and requirements for the database to select the best suitable recovery model. Following listed questions can help you in answering and identifying the availability, requirement and the sensitivity to data loss:

1. Know how important it is to never miss a change in your organization?
2. Will it be easy to recreate the lost data?
3. Do you have any logically consistent database replicas?

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If the answer is yes to the above mentioned questions then you should choose the full recovery database model or Microsoft Distributed Transaction Coordinator.

The pattern of Data Usage

To know the exact pattern, the following questions must be answered by the organizations:

1. What is the frequency of database data change?
2. Are some of the tables modified frequently and significantly?
3. What is the database usage pattern in the critical production period?
4. Is your database subject to risky updates?

Examples of the cases when you should use the Simple Recovery Model

In the following listed conditions, the Simple recovery model may be used:

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• In case if the recovery points are unnecessary, you can use the Simple Recovery Model. If the database is lost then all updates between previous and failure backup will be restored.
• You can take the risk of losing some database.
• You do not wish to take backup and restoring  the transaction log.

Examples of the cases when you should use the Full Recovery Model

In the following listed conditions, Full recovery model may be used:

• You are able to recover all data
• You need to recover to the point of failure
• You want to restore individual page
• You want to incur the administrative cost of the transaction log backup

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Difference between Simple, Full and Bulk-Logged Recovery Model

Here, it is clear that backup and restore operations occur within the recovery model context. The transaction log can be maintained by recovery models. This model controls the way in which the transaction logs are maintained. Many kinds of restore operations are available and the organizations must use the appropriate one. The three recovery models have their own properties and are listed below. Organizations should use the one which is most suitable for them:

Simple Recovery Model and Other Associated Models:

Simple Recovery Model	No log backup is available. Changes can be redone as the most recent backup are unprotected It can recover only to the end of a backup	There is no need to maintain and manage the separate transaction log Log shipping, database mirroring, media recovery features are not available
Full Recovery Model	It requires a log backup The most recent log can be redone	It can recover up to a specific point in time Assume that backups are complete up to some extent
Bulk-Logged	It requires log backups If the log is damaged since the time of recent backup then it must be redone	It can recover the end of any backup It does not support point-in-time recovery

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Final Words:

The blog gives you a depth idea is recovery models in SQL and you can choose the appropriate recovery model as per the usage and project requirements. 

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