Bittu Singh, Author at Tosska Technologies Limited

2022-05-262023-02-18

Measures to Improve Performance of SQL Query?

That’s not bad enough that you call it SQL whereas your boss pronounces it ‘sequel’. But also, you now suffer from “Super Slow Query Syndrome,” and sometimes, your questions bomb without effect.

Don’t worry. We have your back. We recently had a powwow with a lot of caffeine to think about our favorite tips to fix queries. With the help of this article, we will dig into how we can resolve SQL queries and improve the performance of SQL queries with new tips and tricks, such as action plans, references, wild cards, and much more.

In fact, we have combined all our famous skills into one, so you can increase your SQL intelligence by six minutes flat.

The issues faced by the companies in SQL Server performance often lead to focusing on using tuning tools and development strategies. This will help to analyze and process queries faster and eliminate operational issues, troubleshoot poor performance, avoid any chaos, or reduce the impact on the SQL Server database.

What is SQL Query Optimization?

Optimizing SQL Query is the process of writing considerate SQL queries to improve database performance. During development, the amount of data accessed and tested is not much. Thus, it becomes easy for developers to get a prompt response to their raised questions. But the problem starts when the project becomes live and large data starts to flood the database. These kinds of situations reduce the resolving process and performance.

A request for data or information from a database is called a Query, and you need to write a pre-defined set of code that is understandable to the database. Structured Query Language (SQL) and other query languages recover or manage data from related databases.

There are different formats to write a query in the database, using various algorithms. A query that is incomplete or written poorly can lead to a lot of resource consumption, and also can take a lot of time in execution, which possibly causes a loss in services. A proper query can reduce implementation time and lead to better SQL results.

SQL query optimization’s main purpose is to reduce response time and improve query performance, Reduce CPU performance time for faster results and reduce the number of resources used to improve the output.

Ways to Improve SQL Query Performance

Avoiding unnecessary columns in the SELECT section

To improve MySQL functionality, it’s recommended to specify columns in the SELECT section, instead of using SELECT*. As irrelevant columns create more load in the database, it slows down the performance of the whole system.

Using internal joining, rather than external joining if possible

Use external joining only if necessary. Excessive use of it not only limits database performance but also limits MySQL query options, resulting in slower SQL statements.

Using DISTINCT and UNION only if necessary

By using UNION and DISTINCT operators while there are no major objective results in unwanted filtering and reduced SQL performance. To improve the performance and bring efficiency to the process we can always use UNION ALL, rather than UNION.

Using the ORDER BY clause

To get more clear results it is important to use the ORDER BY clause. It not only brings

advantages for database admins but also increases performance in its execution.

SQL Query Performance Tuning: Best Practice

SQL Query tuning is one of the fastest ways to improve the performance of SQL Server. Set procedures and processes are used to improve the performance and resolve the database-related queries this is called Tuning the SQL server. SQL tuning includes several features, including identifying which queries are slower and utilizing them to work more efficiently. Multiple communication databases like MySQL and SQL Server will benefit from SQL tuning.

The Database Performance Analyzer can attempt to troubleshoot server performance issues in the system. But these measures are expensive, and they may not work to solve the problem of slow-moving queries. Tuning SQL functionality helps you to identify poorly written SQL queries and invalid indexing conditions. After doing so, you may find that you do not need to invest in hardware upgrades or technical details.

Tuning SQL functionality can be difficult, especially if done manually. Believe it or not, the slight changes can have major effects on SQL Server and database performance. Hence, there is a need for practical SQL Query performance tools.

To conclude, generally, the best practices of SQL Query performance Tuning include proper indexing that can be done by the Execution Plan tool in SQL Server. Additionally, avoiding coding loops and correlating SQL subqueries.

Tosska SQL Tuning Expert (TSE™) v4 is one of the best SQL tuning tool available in the market. It helps in tuning the SQL even without any source code.

2022-05-022023-02-18

A Quick Guide to Stored Procedures in Oracle Database and SQL

Stored procedures are increasing in popularity in Oracle Database and SQL Server because of quicker execution. Earlier, application code mostly resided in external programs. However, its shift toward database engine interiors compels database professionals to keep their memory requirements in mind.

This is as necessary as planning for times when the code related to database access will be present within the database. They also need to know how they can handle these stored procedures to maintain ideal database performance. We will look at some of these methods and the advantages of using stored procedures and triggers in the Oracle database.

Perks of Stored Procedures for Oracle Database Performance Tuning

Until recently, a majority of Oracle databases had limited code within their stored procedures. This shift in trends is because of the various advantages that come with placing larger amounts of code, such as the following:

Performance Improvement – Using more stored procedures means you don’t require Oracle database performance tuning as much. That’s because each of these only has to load once into the shared pool. Executing them, therefore, is quicker than running external code.

Code Segregation – The stored procedures have all the SQL codes which turn all the application programs into calls for those procedures. This is an improvement in the data retrieval process because changing databases gets simpler.

Therefore, one advantage you get through stored procedures is the ability to transfer large amounts of SQL code to the data dictionary. Doing this will enable you to perform SQL tuning without involving the application layer.

Group Data Easily – You can gather relational tables with data that shares certain behaviour before looking for Oracle performance tuning tips. Simply use Oracle stored procedures as methods, along with suitable naming conventions. For example, link the behaviour of the table data to the table name in the form of prefixes.

The users may then request the data dictionary to display all the traits connected to one table. This makes it more convenient to recognise and reuse code with the help of stored procedures.

Other Reasons Behind the Increasing Popularity of Stored Procedures

There are plenty of other reasons ‌stored procedures and triggers take less time in comparison with conventional code. One of these has something to do with SGA caching in Oracle database and SQL.

Once the shared pool within the SGA gets a hold of a stored procedure, it keeps it there until the procedure gets paged out from the memory. The SGA mostly does this to create space for other stored procedures. The paging out process takes place based on a Least Recently Used or LRU algorithm.

Two parameters help determine the amount of space that Oracle uses on startup. These are the Cache Size and the Shared Pool Size parameters. They also help users check how much storage space is available for various tasks. These include caching SQL code, data blocks, and stored procedures.

Stored procedures will run extremely fast once you load them into the shared pool’s RAM – as long as you can avoid pool thrashing. This is important because several procedures compete for varying quantities of memory in the shared pool.

2022-03-242023-02-18

Why You Must Speed Up Slow Queries in Oracle Database and SQL

The performance of an Oracle database and SQL query speed can directly affect the organisation it belongs to. If the queries running in the database are slow, they will surely have a negative impact. However, its severity may vary based on the database’s role, its architecture, and the industry your organisation operates in.

Regardless of the extent, it would be unwise to ignore them, which is why we are going to talk about all their effects in this blog.

How Slow Statements Affect Oracle Database and SQL Users

In this fast-paced world, everything needs to work fast and offer a quick response time to its end-users. The data that a web page displays generally comes directly from the database with very few interactions.

This implies the dependency of the application’s response time on the time it takes for the queries to run and the database to respond. Slow statements will take more time, resulting in loading screens before the desired information shows up. This is when Oracle database performance tuning becomes a requirement.

Such speeds don’t affect only the application, however; they leave an impact on the other parts of a system as well. The reason behind this is the location of the database in a majority of web architectures.

Take a look at the three-tier architecture, for example – the database lies at the bottom in most cases, forming the foundation. An increase in latency here is likely to cause the same in the higher levels along with other areas in the system.

Another way in which slow queries negatively impact the system is by making the database use more resources than is actually necessary. Some of these are available in limited quantities, such as I/O and CPU, since other applications share these resources.

On the other hand, not using existing resources sufficiently leads to their inefficient usage and slow queries as well. This may be the case with your database, so you may want to consider a few Oracle performance tuning tips that deal with this particular issue.

Top Reasons Behind Slow and Inefficient Queries

Given below are the three most significant causes of queries slowing down:

Too many tasks: Executing a statement includes multiple tasks, such as retrieving data, making calculations, and arranging data in the order as the query specifies. All of these involve plenty of factors, any of which can increase the amount and complexity of work done, from joining and grouping to filtering and sorting.

Too much waiting: Sometimes, statements don’t have too much to do, nor are they stuck waiting for resources. The reason why they are sluggish is that they are waiting on other statements that are locking resources or requiring higher levels of activity.

Too few resources: Query execution works alongside other tasks taking place within a system. This means they share resources such as network throughput, disk I/O, and CPU. Statement execution is likely to take more time when these are completely occupied.

Locating and Working on Slow Queries in Oracle Database

Slow queries don’t get faster on their own – DBAs must take steps to speed them up. For starters, they can use the Database Performance Monitor (DPM) in the following ways:

Viewing all the queries that are taking up execution time using the query profiler. Such queries are often running in the absence of indexes, so it’s a good idea to add one to improve Oracle database performance and execution speed.
Automatically collecting explain plans to get a quick glance at the ones that contain information regarding slow queries and the changes related to them, if any.
Assessing Oracle database and SQL to find out whether a statement can perform better with the help of some improvements.
Visiting the charts page to go through properly arranged metrics pertaining to system performance. This allows the DBA to set a threshold alert and note changes every time a system resource is reaching maximum use.

Conclusion
Based on your architecture and application, slow statements can affect more aspects of your business than just the database. Therefore, ignoring them is not recommended as it often results in a detrimental impact on both end-users and your organisation.
Consider enlisting the help of professional tuning tools to improve slow query performance in Oracle and SQL Server databases.

2022-02-182023-02-19

Tackling Large Tables to Improve MySQL Database Performance

Oftentimes, database professionals make the mistake of jumping to conclusions when trying to improve MySQL database performance. They assume that the database must be the reason why the application has slowed down.

In most cases, they may be right- which is why it’s important to start looking for possible bottlenecks and removing them to reduce lag. However, make sure you consider multiple forms of diagnostic data when attempting to uncover the root cause behind poor MySQL database performance. Don’t stick to just monitoring CPU usage or disk IO as relying on a single metric has greater chances of leading you to an incorrect diagnosis.

We need to look at the full picture to understand the complex interdependencies among CPU, memory, and IO. It is important to do so before making reactive changes, such as increasing disk capacity or memory. In this blog, we will take a look at one such reason behind performance bottlenecks- large data volumes.

How Large Data Volumes Affect MySQL Database Performance

Statements that cover a wide scope of data or are unrefined may fetch unreasonably large quantities of information from the database. This doesn’t seem like a problem at first when the database is new and has minimal data.

The true issue emerges as it grows in size, gradually leading to the requirement of Database Server. This is because when a statement fetches data, the data must be scanned into memory. The bigger the size of the data that needs scanning, the greater the load on the CPU, resulting in the need for burst mode due to sudden CPU spikes. This kind of usage increases the chances of your database server crashing.

Additionally, in case the data does make it from the database server, your app server may not be sufficiently provisioned to handle it. Known as over-fetching, you can overcome this problem by limiting the scope of data selection to relevant records. One way to do that is to opt for the WHERE clause in such queries- after you find them, of course.

The key to locating them is by searching through the database logs and metrics for tell-tale signs of large-scale data fetching. Although you might be able to spot CPU spikes or burst credit utilization from these metrics, it might not be easy to tell which statements are causing this specifically.

Things You Can Do to Improve MySQL Database Performance

Query optimization is one of the best places to begin when you have to improve MySQL database performance. But it differs from case to case and is far from a one-size-fits-all endeavor. That said, there are certain tasks that help in a lot of cases:

As mentioned above, you can prevent large result sets and decrease data volume by limiting the search to relevant records using the WHERE clause.
Go through the database schema to uncover ways that decrease complexity. For instance, keep an eye out on queries that contain a lot of joins since they take more time than most queries. You can make them run faster by reducing their relationships.
A large number of queries also fetch unnecessary fields from tables. You can set them to return only those fields that are important to keep from over-fetching again.
Views can help in some, but not all cases. A view is similar to a table that you can create beforehand by executing a statement to predetermine values that may require on-the-spot calculation otherwise.
Change the syntax of the SQL to influence database SQL optimizer to generate a better query plan.

Conclusion

If your application is performing poorly, the problem often lies with the database, with inefficient queries. While there isn’t any solution that works for every single query out there, database experts can hone in on the ones that require optimization using diligent analysis and monitoring, along with the right SQL optimizer tool for sql server. After they successfully find the queries behind slow database performance, all they have to do is take the right steps to resolve this issue. These include optimization techniques, such as adding indexes, editing out unnecessary fields, and inserting the WHERE clause wherever necessary.

2022-02-162023-02-18

Transferring Data in SQL Server with an Eye on Performance

A lot of database professionals often need to archive older data in SQL Server by transferring it from one table to another. There are multiple ways to achieve the transfer, the most useful of which we will discuss in this blog. We will also provide tips to ensure the performance of the database doesn’t get affected as these approaches are carried out.

Different Methods to Move Data from One Table to Another

Consider the following techniques that various DBAs take when they have to take data from a table to add to another table along with some ways to improve performance of SQL query while using them:

Insert data with the INSERT INTO command – The INSERT INTO query is one of the basic methods of moving data from table 1 to table 2. You can help decrease the time it takes to enter information using this method. If the database is running under the full recovery model, just change it to the bulk-logged model. Doing this saves execution time as it skips over complete logging of bulk operations. The following query should help with this:

ALTER DATABASE <database name> SET RECOVERY <BULK_LOGGED>

Once you switch to the bulk-logged recovery model, you will have to use a truncate statement to flush table 2 (destination). You can carry out the same script you were using to transfer data after this.

Use the SELECT INTO query – Using the SELECT INTO rather than the INSERT INTO command can prove useful in some cases. However, the benefits are significant when the recovery model is bulk-logged due to the reason mentioned above. Although users lack the ability to place the data in an existing table, SQL Server brought with it a feature to make things easier. It essentially enables them to pick the filegroup where they want to create a table.

INSERT INTO query + Tab lock hint – Using both in combination has been known to provide better database performance. To achieve this, you will have to use TABLOCK for table 2. If the destination table is without a clustered index or other constraints, that data will remain as a heap. It helps to use the TABLOCK hint for the destination table during data insertion into a heap using the INSERT INTO statement. Doing this enhances query logging and locking since a shared lock is placed on the whole table rather than every row or page.
Adding data using the SWITCH TO query – You can also try moving the data with the help of the SWITCH TO command. Although this query typically finds its use while transferring information between partitions among separate tables, it can help here as well. How? By moving data from one partition to the next using the ALTER TABLE command. If there are no allocated partitions, the data will transfer through tables instead. Before you begin data insertion, make sure you disable any constraints or indexes that exist on the table. It is better to enable constraints and rebuild indexes after insertion from a performance perspective.

Tips for Enhancing Performance During Data Transfer and Insertion

Reduce IO lag – Latency can negatively impact the process of writing database files on disk. You can decrease latency and bottlenecks using SSD drives that are comparatively better than SATA or SCSI drives.
Maintain Robust Server Infrastructure – The system needs to be properly built to ensure competent performance for various database operations. The greater the pressure on the resources, the greater the effect on performance.
Follow ACID Properties – ACID properties make sure each transaction contains certain properties when it gets processed. In the case of data insertion, the isolation factor is also important to consider because the values have another source. Here, the statements should contain the suitable isolation level to maintain integrity within the database.
Database Settings – One of the best ways to achieve improved outcomes is to maintain the right database configuration. This is because the settings can have a significant effect on performance. For instance, the location of the database files on the disk along with TempDB settings.

These are the various ways in which you can gain better performance at the query, trace, and constraint levels along with additions that can improve the execution of insert operations.

2022-02-162023-02-18

SQL Server: Knowing How Heaps and Clustered Indexes Work

Heaps and clustered indexes are two different ways of storing data in SQL Server. Both have their advantages and disadvantages, and we will discuss them in this post.

A Bit about Heaps

Heaps are essentially piles of data that remain unsorted or unorganized, hence the name. Although you can find heaps on tables that don’t have clustered indexes, they may also be present with non-clustered indexes. Heaps provide the benefit of increased input speed which helps while adding data to a table. Data insertion is quicker because the process doesn’t require a logical order to do so.

A Bit about Clustered Indexes

A clustered index is a more organised way of data insertion. In fact, it is the go-to technique for logically sorting information in a table. A clustered index doesn’t need a primary key but you can create one on a predefined key-value. Most DBAs recommend creating them on the most-used columns that come under reference of highly frequent query executions. They also reduce the need for optimization since all the data gets sorted to fit them. The primary benefit of using a clustered index is that it speeds up data reads.

Knowing When to Use a Clustered Index

As noted above, using a clustered index leads to better read rates. Therefore, there are several instances where you may need to identify whether a clustered index will improve performance of SQL query rather than a heap.

To do this, you need to follow these steps:

First, it is important to understand where there is a requirement for greater read speed.
Check dynamic system views and look for large tables without a clustered index.
Once you locate a few such tables, you can analyse the plans and stats of queries in the MSSQL system dynamic management views. Searching through the table name in the variable will show you the usage frequency of the plan. It will also show the text fetched and other necessary validation details that show whether a heap or non-clustered index is in use instead.

You will be able to view object names in the second result set in case the table in question is under use in SQL object. Once you have reviewed the query plans relevant to the use cases, you will have sufficient information to help you decide whether the table requires a clustered index or if a heap is more suitable for it. You will also have to choose all the columns that will have to be in the index in case of the former. Tables with several use cases that mostly share the same columns can provide result sets faster with a clustered index.

When Not to Use Clustered Indexes

This is just as important to know because believe it or not, there are instances where a clustered index can do more harm than good to oracle database performance.

A logging table is one such instance as it normally has far more insert operations than reads or updates. This is because their purpose is to log each occurrence but users may not refer to it as frequently. If you place an index on this kind of table, it can result in hot latches due to lagging data insertions for the last available page. Meanwhile, information keeps getting added onto the same page from other means. The one case where this issue doesn’t occur is when the index’s main column is a GUID, therefore, it isn’t sequential.

Using a clustered index in a table with an excessive number of columns isn’t the best idea, either. The reason behind this is simple: the index is supposed to define the default sort order. Too many columns mean repeated resorting with each new use case, slowing down the database. It will also result in an increase in the size of the non-clustered indexes present in the table.

Another situation where a clustered index can’t help is a column that isn’t usually static as they undergo frequent changes. Changing key values on an index have far greater chances of creating performance-related problems. This is because updating key values typically leads to page splits – these need maintenance, which takes resources and affects performance.

2022-01-142023-02-18

Tackling Large Tables to Improve MySQL Database Performance

How Large Data Volumes Affect MySQL Database Performance

Things You Can Do to Improve MySQL Database Performance

As mentioned above, you can prevent large result sets and decrease data volume by limiting the search to relevant records using the WHERE clause.
Go through the database schema to uncover ways that decrease complexity. For instance, keep an eye out on queries that contain a lot of joins since they take more time than most queries. You can make them run faster by reducing their relationships.
A large number of queries also fetch unnecessary fields from tables. You can set them to return only those fields that are important to keep from over-fetching again.
Views can help in some, but not all cases. A view is similar to a table that you can create beforehand by executing a statement to predetermine values that may require on-the-spot calculation otherwise.
Change the syntax of the SQL to influence database SQL optimizer to generate a better query plan.

Conclusion
If your application is performing poorly, the problem often lies with the database, with inefficient queries. While there isn’t any solution that works for every single query out there, database experts can hone in on the ones that require optimization using diligent analysis and monitoring, along with the right SQL optimizer tool for sql server.
After they successfully find the queries behind slow database performance, all they have to do is take the right steps to resolve this issue. These include optimization techniques, such as adding indexes, editing out unnecessary fields, and inserting the WHERE clause wherever necessary.

2022-01-142023-02-18

The Importance of Disk Operations in Query Performance Tuning

DBAs can’t ignore disk operations when working on query performance tuning. When talking about databases, ‘disk’ may be called by one of its many names, such as ‘storage’, ‘I\O’, ‘Reads’, or disk operations.

Although database professionals know all these terms mean the same thing, these might confuse those outside this field. When referring to one of these terms, they usually mean the number of disk operations required to fetch the data from the Disk resource.

Why You Can’t Ignore Disk Operations During Query Performance Tuning

The fact remains, however, that an overwhelming majority of SQL Server databases face the bottleneck issue when it comes to the disk resource. This doesn’t change, regardless of whether you have old-school hard drives or the latest flash storage arrays. Given below are some major reasons behind this, and how these can be affected with MySQL query optimization:

Most slow queries are slow because they have to scan a large amount of data. A lot of the time, this is unnecessary and it’s making your SQL Server perform a lot of unneeded and really sluggish read operations.
When the database reads data, it requires a place to store that information- which it does in the RAM. However, since the RAM has a limited capacity, older information starts getting removed with newer data coming in.
Because RAM is never enough, it is often unable to store all the data that SQL Server fetches. Therefore, the remaining data has to be kept on the disk, which is far slower than the RAM. The information that isn’t present in the RAM has to be fetched from the disk- an operation that is known as the slowest in all of the database operations. Some DBAs even compare data fetching from the RAM and the disk to sprinting and tip-toeing.
So, if we tune a query to read less data than it did before, such as twenty rows instead of twenty thousand, it will help in two ways. Not only will it reduce the workload on the database in terms of disk operations, but it will also require far fewer resources, including CPU and RAM, to process all the data. That said, the end-user is unaware of all these operations- all they know and appreciate is the speed or the time it takes for the query to fetch information. To put it simply, they just want the screen on the app to return as quickly as possible. This is why query performance tuning focuses on decreasing disk reads.
DBAs also perform tuning to lower the other resources, such as CPU or RAM usage. But they only do this in certain special situations where such resources are consistently being overused at dangerous levels. For instance, if the CPU is in constant use of 90% or above, then the DBA will consider CPU tuning.
Tuning queries that fetch large volumes of data to fetch much smaller volumes instead improves SQL Server capacity. This is because when a query takes up fewer resources, it leaves room for more users and queries. This allows the same server to take greater loads than it could. Performing MySQL query optimization also improves the lifespan of the same server, delaying the requirement for a hardware upgrade.

Summing Up

The above-mentioned reasons shed light on the fact that disk operations play a major role in enabling efficient database query performance. You can’t always blame the CPU; in fact, you can rarely do so since 95% of bottlenecks occur on the disk resource.

The CPU, on the other hand, is only a lagging indicator whose use can decrease if the storage reads differ.

2021-12-132023-02-18

Backup and Recovery in SQL Server: Understanding the Basics (Part 2)

This blog is the continuation of the 2-part series to explain recovery models in SQL Server.

Each of these aims at different requirements to provide partial or complete data recovery. The Database Administrator selects the recovery model depending on the resource and data requirements of the organization. The goal of the recovery model is to balance the logging overhead with data recovery criticality.

Types of Recovery Models for SQL Server

Given below are the recovery models you can use in your backup and restore strategy:

Simple: This model does not support transaction log backups. SQL Server directly truncates the checkpoint operations log when using this recovery model. This frees up transaction log space to store additional transactions.

Although the Simple Recovery model is the simplest with regards to t-log backup management, it makes the user unable to carry out point-in-time database restores. This can lead to devastating data losses when your data changes on a frequent basis and your backups (full or differential) aren’t run regularly.

In other words, the frequency of your backups will determine the amount of data loss you are likely to experience if you have to restore your database using the Simple Recovery model.

Full: The use of this model will ensure the t-log file holds all your transactions until you run a t-log backup. No automatic truncation will take place here, unlike in the Simple Recovery model. Moreover, the Full Recovery model enables users to restore their database to any point in time as long as the transaction log backup has it. This minimizes data loss but is more likely to affect oracle database performance.

It is important to remember when using this model that the t-log will keep saving information as you make changes to the database. Therefore, you’ll have to carry out transaction log backups on a frequent basis to keep them from getting too large. Creating a t-log backup clears the previously-stored data, making space available to store new transactions.

The amount of disk space the transaction log takes does not change, nor should the user expect it to do so. That said, while you will have to pre-size the transaction log on the basis of expected activity, you can set its size to auto-grow in case it uses up all of its space. However, try to refrain from shrinking these files unless you don’t have a choice. These files are typically shrunk with the help of T-SQL commands in SQL Server.

Bulk-Logged: It shares a lot of similarities with the Full Recovery model, except for its minimal logging feature. In it, certain bulk operations aren’t fully logged in the transaction log, such as TRUNCATE, BULK import, and SELECT INTO. These operations are called minimally logged operations, thanks to which your t-logs won’t grow as much in size as compared to the Full Recovery model.

On the other hand, this type of operation keeps users from carrying our point-in-time restores. This is a disadvantage for many as it increases the chances of critical data loss. Therefore, experts recommend sticking with the Full Recovery model in cases where you’re unsure whether this model is the perfect choice according to your requirements. Despite its performance-affecting results, you will be able to guarantee data availability. You can still use SQL tuning tools to rectify this issue.

In Conclusion

Using the right recovery model, you can recreate and restore the entire database data in one step. This process overwrites the current database or creates it in case the database no longer exists. The ‘new’ database will be identical to the condition of the database when the backup took place, without the proceeding uncommitted transactions. These are rolled back once database recovery has taken place.

2021-12-132023-02-18

Backup and Recovery in SQL Server: Understanding the Basics (Part 1)

Taking regular database backups is essential to provide assistance to businesses recovering from an unplanned event. They enable data restoration from when it was previously saved. Moreover, keeping a copy of the information separately is also vital for protection against corruption or data loss.

In this 2-part series, we’ll cover

In this guide, we will discuss SQL Server backup types, recovery models, as well as best practices that you should take into account when putting together your backup strategy.

Various Types of Backups in SQL Server

There are different backup types in SQL Server that users have to consider when constructing their backup strategy. Here, we will briefly explain each of these variants and how they work. Microsoft SQL Server supports the following backup forms:

Full Backup: This implies a complete backup of the SQL Server database. It covers every object in the database. It is the most popular and recommended backup type as it enables users to restore their database to the exact same version it was when the backup was taken.

Differential Backup: It backs up only the data that has undergone changes since you created the last full backup. This is why it takes lesser time than a full backup. However, creating several differential backups over time may eventually lead to greater storage requirements.

The size increases because of the addition of changed data in each subsequent backup, and it can grow to become as large as the full backup. Thus, it is important to schedule new full backups (even if they’re less frequent) to avoid extended backup times and oversized differential backups. Otherwise, these excessively-large backups will cause a negative impact on database performance, requiring optimization.

Transaction Log Backup: It is a form of incremental backup. It backs up the transaction log containing the modifications made since the last t-log backup. Log backups can take place quite frequently – even once every few minutes. This enables users to carry out point-in-time restores to reduce data loss.

File/filegroup Backup: This type of backup involves making separate copies of individual data files or files from a filegroup. Users can backup and restore each database file separately as well.

Copy-only Backup: This is a type of SQL Server backup that doesn’t depend on the sequence of traditional backups. When you create a backup, it generally makes changes to the database. These impact the manner in which these backups will be restored in the future. On the other hand, it may sometimes be more useful to create backups that don’t affect the comprehensive backup and restore methods for the entire database.

Creating Backups for SQL Server Databases: What Experts Suggest

Seasoned database professionals recommend a few things when it comes to creating backups of the database. For starters, they suggest using the full recovery method on a daily basis. However, you may create these on alternate days and differential backups every day if the database size exceeds three GB.

Many also advise making daily t-log backups once you’ve created a full or differential backup. You may even schedule one for every four hours, and avoid truncating one manually. If disaster strikes, it’s better to create a backup of the t-log that’s active at the moment. In case there isn’t any t-log backup available, you’ll be unable to restore database activities past the latest available t-log backup. This is likely to hinder point-in-time recovery as well.