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Introduction to JUnit BeforeClass

JUnit beforeclass is used when executing a common operation before every test. In junit java, it is preferable to execute the same before running all the tests by using beforeclass. Therefore, junit beforeclass is annotated by using @BeforeClass. The beforeclass method will run before executing the test from the current class. Junit beforeclass is a critical and valuable annotation in the java framework.

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What is JUnit BeforeClass?

Sometimes we need to share the test computationally. So it will compromise the independent test. Sometimes, it is optimization.

While annotating the @BeforeClass method with the main method, it will cause the method will run before the test methods in a class.

The @BeforeClass method runs before the current class or will be shadowed in a current class.

The beforeclass annotation will indicate that the static method is attached and executed once before all tests into the specified class. For example, it will happen when the share method shares an expensive setup computationally.

JUnit BeforeClass Annotation

The junit beforeclass annotation is used in junit version 4 and junit version 5. The beforeclass annotation method will execute all the test methods when the test class is executing.

The beforeclass annotation is used when we need to set up test data or resources at the class level.

The beforeclass method will be annotated with @BeforeClass or @BeforeAll, executing once per test class.

As we know that beforeclass annotation will be executed once in class, and the copy of the beforeclass annotation method will be shared across the class. Therefore, the way we are using beforeclass annotation is static.

If suppose in beforeclass, we are using 5 test cases and annotating the same using @BeforeClass. It will execute the test class once before any TestCase initiates its execution.

Below is an example that shows how we are using junit beforeclass annotation in our code. In the below example, we have created a class name as BeforeClass. First, we are creating a name as before_class; we have defined the @BeforeClass method in that method. Also, we are creating two test cases with method names case1 and case2. In both methods, we are using the @Test method annotation.

Code:

public class BeforeClass { @BeforeClass public void before_class () { System.out.println ("Before class method"); } @Test public void case1 () { System.out.println ("Case1"); } Test public void case2 () { System.out.println ("Case2"); } }

JUnit BeforeClass Type

When writing test cases, it is common to find several tests similar to the object created before it runs.

While annotating the public void method with the beforeclass method will run before the test method.

The before-class superclass method runs before the class, which was current unless it was overridden as an existing class.

The beforeclass type method is executed only once in a code. The before annotation is used in a method containing java code running before the test case.

All the junit method is annotated with the beforeclass method. Junit beforeclass will run before the test class, but it will run as per order.

When working with beforeclass annotation, it’s possible to run the method once per the entire class before test execution. However, it is time-consuming to open and close the resources in every test after opening servers and communication. It happens by using @BeforeClass annotation.

The below example shows junit beforeclass types as follows. In the below example, we have created a class name as BeforeClass_Type. First, we are creating a name as before_class; we have defined the @BeforeClass method in that method. Also, we are creating two test cases with method names Class_Type1 and Class_Type2. In both methods, we are using the @Test method annotation.

Code:

public class BeforeClass_Type { @BeforeAll public void before_class () { System.out.println ("Before class type"); } @Test public void Class_Type1 () { System.out.println ("Class_Type1"); } @Test public void Class_Type2 () { System.out.println ("Class_Type2"); } }

Output:

Examples of JUnit BeforeClass

Below are steps shown to create junit beforeclass as follows. We are making the project name as JunitBeforeclass.

In this step, we create the project template of junit JunitBeforeclass in spring boot. We provide the project group name as com. For example, the artifact name is JunitBeforeclass, the project name is JunitBeforeclass, and the selected java version is 11. We are defining the version of spring boot as 2.6.7.

Group – com.example

Artifact name – JunitBeforeclass

Name – JunitBeforeclass

Spring boot – 2.6.7

Java – 11

Package name – com.example.JunitBeforeclass

Project Description – Project for JunitBeforeclass

In this step, we extract the downloaded project and open the same by using the spring tool suite.

In this step, we check all the project structure and its files. Also, we are checking whether that chúng tôi file is created or not. If this file is not created, we need to create the same manually. However, this file is created in the below example, so we do not need to create it manually.

Code:

The below example shows junit beforeclass as follows. In the below example, we have created a class name as Junit_BeforeClass. First, we create a name as junit_before_class; in that method, we define the @BeforeClass method. Also, we are creating two test cases with method names test2 and test3. In both methods, we are using the @Test method annotation.

Code:

public class Junit_BeforeClass { @BeforeAll public void junit_before_class () { System.out.println ("Junit before class"); } @Test public void test2 () { System.out.println ("Test2"); } @Test public void test3 () { System.out.println ("Test3"); } }

Output:

Conclusion

The @BeforeClass method runs before the current class or will be shadowed in a recent class. It is used when executing a common operation before every test. For example, sometimes, we need to share the test computationally.

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Methods And Examples Of Postgresql Backup

Introduction to PostgreSQL Backup

If you are using the PostgreSQL database in the production environment for your clients, you need to ensure that your database is always working fine and available 24 * 7. For the availability of the database, you must often keep a backup of your client’s database. To ensure data restoration in the event of database corruption, crashes, or loss, you must have the ability to restore the data. For this reason, PostgreSQL provides us with a facility to keep the backups using three methods –

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Methods of PostgreSQL Backup

Three methods of PostgreSQL backup are given below:

1. SQL Dump 2. File System-Level Backup tar -cf chúng tôi /etc/psql/12/data 3. Continuous Archiving

This methodology combines the File system-level backup methodology and Write Ahead Logs (WAL) stored in pg_xlog. The database maintains logs for each and every transaction performed on it. To determine the successful completion and commitment of a transaction, the system maintains a checkpoint. Whenever a crash occurs or data is lost. To recover the database, you can restore the data stored in the file-based system and then apply the logs from that point until the checkpoint to bring the database to its current state. However, this process is a bit clumsy and complex but provides some benefits over the other two, as discussed previously.

In the upcoming session, we will briefly discuss the SQL dump method, which we consider the most convenient and preferred approach.

Explanation of SQL Dump

Furthermore, the database operations continue to run while pg_dump is in progress and not locked. However, it is important to note that certain operations, like ALTER TABLE, which are related to structural changes, will be blocked during the execution of pg_dump. You must specify external -o in the pg_dump command if your database schema depends on OIDs such as foreign keys. For this, you will also need to dump the OIDs.

Syntax:

pg_dump: It is the utility program provided in PostgreSQL to store the current state of the database into a file containing commands which, when run on the database server, will recreate the state of the database when it was dumped using the same. To run it, you need to execute pg_dump as a client-side program through the Linux command line prompt.

databaseName: It is the database name you want to dump.

outputFile: It is the file name that has to be created after the dumping is finished.

The execution of the pg_dump process is limited to the superuser login because only the superuser has the necessary permissions to read all databases and tables. Although, you do have a facility to dump the database remotely. By default, the environment variables PGHOST, PGPORT, and PGUSER consider the localhost, port 5432, and the username associated with the operating system as the default values for connecting to the database.

You can change the PGHOST and PGPORT by using the options -h for the host and -p for the port in the pg_dump command. To change and override the PGUSER variable, you can use the -U option in the statement. Client authentication mechanisms confirm all of this.

Example:

Check whether the file is created successfully. Let us use the ls command, which lists all the files in the current directory –

ls

Output:

Now, we have a ready backup file named “myBackupFile” that has been dumped.

Let us see the contents of the Postgres database by checking all its tables with the help of the dt command.

c postgres dt

Output:

So, it contains three tables which we will drop one by one. By using the commands

drop table educba; drop table teams cascade; drop table developers;

and then further check whether all of them are deleted by dt command.

dt

So, now the database Postgres does not contain any tables in it. Now, we will learn how to restore the data to the database.

Restoring the Dump

Having a backup file allows us to restore the database at any time, which proves helpful in situations where the database becomes corrupted or is lost.However, it would be best if you considered some things before restoring. The database you are trying to restore should be on the server. If not, then you should create the database with the help of the command

createdb -T template0 Postgres

in our case. Since the database already exists, you can verify its presence by using the command l, which displays the following output from the database server. Therefore, there is no need to execute the createdb command now.

l

Output:

The other thing is to ensure that the database you are restoring should already consist of all the users with the right to it. In our case, the Postgres user owns the Postgres database. Hence, a database server should already have a user named Postgres, or it will give an error while restoring. You can check this by firing the command –

SELECT usename FROM pg_catalog.pg_user;

which results in the following –

Now, the Postgres database and user are already in my database server. I can go for restoring the database using the command –

psql postgres < myBackupFile;

as the syntax of restoring the dump is

psql empty_database < backup_file psql postgres < myBackupFile;

Output:

Now, if we check the contents of the Postgres database using the command dt, it gives the output as –

dt

Output:

Also, the contents of all the tables are restored correctly –

select * from developers;

Output:

Handling Restoration Errors

In PostgreSQL, the restoration process persists even if an error occurs in between. It only tells about them at the end of the completion of the restore. In this case, the database is restored incompletely. If you want to stop the restoration process on error occurrence, you can use –

psql --set ON_ERROR_STOP=on postgres < myBackupFile

ON_ERROR_STOP option helps you to stop the restoration process whenever the error occurs. To restore the database in a transactional manner, where only the entire database is restored or no changes are made, you can use the “-1” or “–single-transaction” option. This option ensures that the restoration process operates as a transactional process.

psql -1 postgres < myBackupFile

For dumping all the databases in the current database server to a file, you can use the pg_dumpall utility program and provide the default database while restoration.

Conclusion – PostgreSQL Backup

We can dump our database so that a backup is available in the near future to restore the database in case of any problem with data available from the database using pg_dump in PostgreSQL. You can utilize other methods, including File system level backup and Continuous archiving, to maintain backups of your PostgreSQL database.

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Overview And Various Examples Of Jquery Keydown()

Overview of jQuery keydown()

The jQuery keydown() method is used to handle the key down event which is generated by pressing the keyboard button. This is a built-in method in jQuery. This method is used to handle the keydown event which is generated by pressing the key on the keyboard and the keydown() method handle the event by executing associated function.

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Keypress() event: This event is generated when the key is pressed down.

Keyup() event: This event is generated when the key is released.

The order of an execution of the jQuery event methods is:

keydown() event

Keypress() event

Keyup() event

The syntax of the keydown() method:

$(selector).keydown(): This method triggers the keydown event for selected html elements.

$(selector).keydown( function ): This method triggers a function to the keydown event for selected html element.

Parameter:

Function: This is an optional parameter. It specifies the name of the method which is to be executed when the keydown event is generated.

Examples of jQuery keydown()

Example of jQuery keydown ( ) method with parameters are as follows –

Example #1

Next, we write the html code to understand this method more clearly with the following example where we apply the keydown() method to the first input text box element

Code:

$(document).ready( function(){ $( “input” ).keydown( function(){ $( “input” ).css( “background-color”, ” red “); }); });

Output:

Once we press the key in the text box, the output is –

Example #2

Next, we rewrite the html code to understand the jQuery keydown() and jQuery keyup() method more clearly with the following example where we apply the keydown() method and jQuery keyup() method to the first input text box element –

Code:

$(document).ready( function(){ $( “input”).keydown( function(){ $( “input”).css( “background-color”, ” red “); }); $( “input”).keyup( function(){ $( “input”).css( “background-color”, ” yellow “); }); });

Output:

Once we press the key in the text box, the output is –

As in the above output, the keydown() method triggers the event and handle the keydown event of the selected elements in the jQuery collection, If we write something in the text box then the text box colour changes red on keydown and yellow on keyup events, as showing in the above output.

Example #3

Code:

$(document).ready(function(){ $( “input” ).keydown( function(){ $( “input”).css( “background-color”, ” red “); }); $(“input”).keyup(function(){ $( “input”).css( “background-color”, ” yellow “); }); $(“input”).keypress(function(){ $( “input”).css( “background-color”, ” black “); }); });

Output:

Once we press the key in the text box the background colour change to black and key release the background colour change to yellow, the output is –

When we press the backspace key in the text box then only the jQuery keydown() method is executing, otherwise, on keypress, the jQuery keypress() method is executing and the output is –

Conclusion

The jQuery keydown() method used to handle the key down event.

The keydown event is generated by pressing any keyboard button.

It is a built-in method in jQuery.

The method is used to handles the keydown by executing an associated function.

The keydown() event is usually used with other two events, which are Keypress() event ( generated when the key is pressed down) and Keyup() event ( generated when the key is released).

The syntax of the keydown() method is $(selector).keydown() and $(selector).keydown( function ), the parameter function is an optional parameter. It specifies the name of the function which is to be executed when the keydown event is generated.

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Learn The Overview And Examples Of Jmeter Script

Introduction to JMeter Script JMeter script overview

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JMeter script run

The procedure to execute JMeter scripts and Loadrunner configuration, and runtime configuration is explained below.

Install the JMeter, the latest version 64-bit JDK or JRE, in all the load generator machines where the script needs to be executed.

Compose the scripts in JMeter and save them in a local folder. The script should be saved in ZIP format and have all the files in the test script folder. The file’s path in the script folder should not surpass 260 characters.

CSV files can be downloaded manually on the load generator executed on JMeter concerning the path in the script location.

Upload the script of the JMeter into the Loadrunner enterprise.

In the navigation toolbar, choose test management. Next, choose the destination folder, or the user can create a new one.

Choose the upload script button from the navigation pane.

Upload settings should be configured and update the selected scripts in the destination folder.

After uploading the scripts of JMeter to Loadrunner, then choose the script in the test management tree and display the script to view the description.

In the workload and group view option, choose Vuser groups and edit runtime. After which, the dialog box pops up with JMeter runtime settings.

The JMX measurement is a UI element used to enable the JMX measurements at performance test execution.

The JMeter path is used to enter the default values in the JMeter script by including environment variables of %JMETER_HOME%

JMeter port is used to select the default port, which begins from 4000, and it uses the alternate port if the default port is already occupied. The range of the JMeter port lies from 4445 to 4455.

Remote testing is used to execute JMeter in node mode or server mode. Execution of JMeter can replicate the test among low version computers which simulate maximum load on the server.

JMeter additional file is used to give the local path for remote load generator, which can also be used as remote JMeter nodes or JMeter controller. It is enabled when remote testing is selected. Ensure that added properties are placed in the local path of the remote load generator, which is used as remote JMeter nodes or controllers when the test is executed.

Give a LoadRunner enterprise test and align the JMeter script with it.

Execute the test from the JMeter.

JMeter script with Examples

Cloud provisioning can be implemented to make the JMeter scripts more reliable to the host machine. Furthermore, it signifies that the JMX scripts on the cloud give effective cloud provisioning methods where the customer doesn’t want to pay and use it for free to execute the cloud test. To define the cloud location, choose the list of available locations, fetch cloud tokens from API keys and run the modules. If the user wants to specify multiple cloud locations for the same execution, it distributes the throughput and concurrency among all the locations.

The JMeter scripting can also be automated with Jenkins to achieve maximum efficacy. Continuous delivery becomes more fascinating in Software as a service company to create a new website and continuously work to enhance it. Software development has been growing in terms of automating the process, testing the behind lags, increasing the performance, minimizing the execution time, finding the bugs easily, and so on. By using Jenkins in executing a shell in JMeter, the project configuration is executed to make an effective continuous delivery cycle.

Conclusion

The JMeter script is used to access reporting services. For example, many testing tools aim at execution; the reporting features help access the test results in an interactive method. In addition, monitoring execution time helps find and access the JMeter scripting in a better method.

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Examples Of Ebit (Earnings Before Interest And Taxes)

Definition of EBIT

EBIT, i.e., earnings before interest and taxes, refers to the earnings of the business before taking into account the interest and the tax payments or other words, EBIT is a measure of any company’s profitability from its normal operations as the EBIT is calculated by deducting the total of operating expenses from the total of sales revenue. In this topic, we are going to learn about EBIT Calculation.

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The formula for EBIT Calculation

EBIT measures the business’s profitability from its operations as it does not consider the expenses relating to interest and taxes. EBIT is also known as the company’s operating income as it shows the company’s earnings from normal business operations, neglecting the effect of the interest and tax expense on the business profits. Two methods can calculate the EBIT of the company. The first method is subtracting all the company’s operating expenses from the sales revenue, and the second one is to add up interest expense and the tax expense in the company’s net income. A formula can be illustrated below:

1. First Method (Direct)

Earnings Before Interest and Taxes (EBIT) = Revenue During the Period – Cost of The Goods Sold– Operating Expenses

In this case,

Revenue during the period is the total amount of revenue earned by the company during the period under consideration by selling the goods or providing the services.

The cost of the goods sold is the total amount of cost incurred by the company during the period under consideration for the goods it sells or services provided to the customer.

Operating expenses are the expenses that a company incurs for operating its business.

2. Second Method (Indirect)

The formula for the Indirect Method is:

Earnings Before Interest and Taxes (EBIT) = Net Profit Earned +interest Expense + Tax Expenses.

In this case,

Net profit is the profit the company earns after deducting interest and taxes during the period under consideration.

Interest expense is the expense that the company makes during the period on any of its borrowings.

Tax expense is the expense payable by the company during the period to the tax authority.

Examples of EBIT

Following are the examples are given below:

Example #1

There is a company, XYZ incorporation, in which Sales revenue during the financial year 2023-20, as per the income statement, is $500,000. During the current financial year, the company’s cost of goods sold is $200,000; its operating expense is $100,000. Interest expense is $25,000, tax expense is $20,000, and the net profit is $155,000. Compute the EBIT of the company.

Solution:

In this case, EBIT can be computed during two methods below:

 First Method (Direct)

Earnings Before Interest and Taxes (EBIT) is calculated as

Earnings Before Interest and Taxes (EBIT) = Revenue During the Period – Cost of The Goods Sold– Operating Expenses

Earnings before interest and taxes (EBIT) = $500,000 – $200,000 – $100,000

Earnings before interest and taxes (EBIT) = $200,000

Particulars 

Amount ($)

Sales Revenue 5,00,000

Less: Cost of goods sold 2,00,000

Less: Operating expense 1,00,000

Earnings before interest & taxes [EBIT] 2,00,000

Second Method (Indirect)

Earnings before interest and taxes (EBIT) is calculated as

Earnings before interest and taxes (EBIT) = Net Profit Earned +interest Expense + Tax Expenses

Earnings before interest and taxes (EBIT) = $155,000 + $25,000 + $20,000

Earnings before interest and taxes (EBIT) = $200,000

Particulars

Amount ($)

Net Profit 1,55,000

Add: Interest Expense 25,000

Add: Tax Expense 20,000

Earnings before interest & taxes [EBIT] 2,00,000

So, the company can calculate the operating profit or EBIT using the two methods above.

Example #2

The total sales revenue of the company was $1,000,000

Total Purchases were $550,000

Opening and closing inventory was $50,000 & $70,000, respectively.

Salary & wages paid were $150,000

Rent Paid was $60,000

Depreciation expenses were $30,000

Interest expenses were $20,000

Taxes paid were $30,000

Now calculate EBIT from the above figures.

Solution:

Earnings before interest and taxes (EBIT) = Revenue during the period – Cost of the goods sold– Operating expenses

The cost of The Goods Sold is calculated as

Cost of The Goods Sold = Opening Stock + Purchases – Closing Stock

Cost of The Goods Sold = $50,000 + $550,000 – $70,000

Cost of The Goods Sold = 530,000

And,

Operating expenses are calculated as

Operating Expenses = Salary & Wages + Rent Paid + Depreciation Expense

 Operating Expenses = $150,000 + $60,000 + $30,000

Operating Expenses = $240,000

So,

EBIT = Revenue During the Period – Cost of The Goods Sold– Operating Expenses

EBIT = $1,000,000 – $530,000 – $240,000

EBIT = $230,000

Particulars 

Calculation

Amount ($)

Sales Revenue

10,00,000

Less: Cost of goods sold

{opening stock[A] 50,000

Purchases[B] 5,50,000

Closing stock[C]} 70,000

COGS[A+B-C]

5,30,000

Less: Salary & Wages

1,50,000

Less: Rent Paid

60,000

Less: Depreciation expense

30,000

Earnings before interest & taxes [EBIT]

2,30,000

Thus the company earned EBIT of $230,000 during the current year.

Example #3

Suppose in the above example we are given the information like the following:

Particulars 

Calculation

Amount ($)

Sales Revenue

10,00,000

Less: Cost of goods sold

{opening stock[A] 50,000

Purchases[B] 5,50,000

Closing stock[C]} 70,000

COGS[A+B-C]

5,30,000

Less: Salary & Wages

1,50,000

Less: Rent Paid

60,000

Less: Depreciation expense

30,000

Less: Interest Expense

20,000

Less: Current year Taxes

30,000

Net income

1,80,000

And now, we calculate EBIT using the Indirect Method:

Solution:

Calculation of EBIT using Indirect Method:

Earnings Before Interest and Taxes (EBIT) = Net Profit Earned + Interest Expense + Tax Expenses

EBIT = 1,80,000 + 20,000 + 30,000

EBIT = 2,30,000

Particulars 

Calculation

Amount ($)

Net income

1,80,000

Add: Interest Expense

20,000

Add: Current year Taxes

30,000

Earnings before interest & taxes [EBIT]

2,30,000

Conclusion – EBIT Calculation

Hence, EBIT is the business’s earnings before deducting the interest and the tax expense from the revenues. The measure of EBIT is important to know the business’s financial performance, i.e., how efficiently the company is managing its routine operations to generate revenues. EBIT ignores the cost of finance and the burden of taxes, which are deducted while calculating the company’s net income.

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Working Of Transactions With Examples

Introduction to MongoDB Transactions

MongoDB transactions are provided in version 4.0 of Mongo DB where the transactions are supported even in Multi-document operations to maintain the ACID properties. The transactions are supported even across the sharded clusters and the replications of the documents in the Mongo database. There arise many situations where we need a transaction to maintain the atomicity in the operations where the process consists of multi-collection data or multi-document data which is supported by MongoDB transactions.

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In this article, we will have a look at the necessity of the transactions in MongoDB, the ACID properties of the transactions, and have a look at sample examples to demonstrate the use of Mongo DB transactions in your application.

MongoDB Transactions

There are multiple read and write operations being done from and to the Mongo DB database that needs a behavior where all those set of operations should be completed entirely or none of them should be reflected in the database. This integrity of a set of read and write operations is maintained by using transactions.

ACID properties of transactions

All the transactions in Mongo DB follow the properties of ACID which stand for Atomicity, Consistency, Isolation, and durability. It is important for exhibiting all these four characteristics inside your transaction for validation. Let us discuss one by one what all these four properties of ACID stand for –

Atomicity – By this property, we mean that all the operations that are present inside the transaction will together be treated as a single unit which means that the failure of even a single operation will lead to a rollback of all the previously executed operations of that transaction and marking the failure of the transaction. Inversely, if all the operations are executed successfully the transaction is also succeeded.

Consistency – By consistency in the database what we mean is that any changes in data will lead to the satisfaction of all the constraints applied on that column of a field in a database. For example, when a unique key is assigned to the document inside a collection then the field is always kept unique while maintaining its consistency.

Isolation is the property that helps in explaining the segregate execution of each transaction when multiple transactions are running in the system simultaneously.

Durability – Durability means the changes in the data being made in the database persist and are stored in the backing store as well which means is there is any kind of system failure arising then the data won’t be affected and will be stored and maintained properly.

Working of Transactions

We have to initiate a session in MongoDB with the help of the driver.

Further, you can make use of this session for executing all the operations that you wanted your transaction to carry out. This operation can be having the involvement of multiple documents, collections, and also across sharded clusters and all of them being ACID compliant.

Limitations of using transactions in MongoDB

There are many limitations while using the transactions in MongoDB which are as listed below –

Read operation cannot be performed on system collections.

Write operation cannot be done on non-existing collections or capped collections.

Indexes and collections cannot be modified or dropped in the transactions.

Example

Consider the following example of a transaction in Mongo DB.

The output of the execution of the above code snippet is as shown in the below image –

Further, we can decide if we want to commit the transaction or abort it by using the following statements –

sampleSession.abortTransaction()

Conclusion

The transactions can be single-document, multi-document, or even involving multiple clusters in it in the case of a distributed system. In Mongo DB the single document transactions are maintained internally. However, in the case of multi-document transactions, there is an extra overhead of managing these transactions. Transactions following the ACID properties make their database consistent, atomic, durable, and isolated. There are multiple methods using which we can initiate the session and abort or commit or transaction in Mongo DB.

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