Updated June 3, 2023
Introduction to MySQL Asynchronous
MySQL Asynchronous is a technique to support an asynchronous query execution in the server, which defines not prevailing or arising at the equivalent interval.
Conventionally, the asynchronous approach was applied by various MySQL drivers while executing MySQL query statements. In this concept, some operations could take a long time to accomplish, like executing query commands and opening connections were congested awaiting completion. Thus, to resolve this issue or find a solution, a MySQL developer needs to inscribe a multithreaded application allowing analogous query execution processes in the MySQL server. This gave rise to the asynchronous approach using the X protocol.
Syntax
Let us evaluate the syntax structure for MySQL Asynchronous concept as follows:
In MySQL, an Asynchronous function is nothing more than a MySQL function that guarantees to yield a promise. A user can implement it like any other programming language function we use that results in a promise:
async function funA(){
return 50;
}
funA().then( result => console.log(result));The above code presents a simple function syntax to use the async function in MySQL, which, when executed, generates the outcome 50 or, say, prints 50.
Besides this, along with the async function in MySQL, you can also add the keyword await, with any promise and not only to invoke other async functions:
const funA = Promise.resolve(50);
console.log(await funA);This function code also produces the output as 50, same output as the previous one. This is vital since we can wrap any present function that applies callbacks to yield a promise and invoke that function by the async/await arrangement.
How asynchronous function work in MySQL?
A very mutual way to apply MySQL Asynchronous operations is using callbacks. In MySQL, when a callback function is provided, the CRUD operation becomes non-blocking, meaning that the subsequent statement is executed immediately without waiting for the result from the database. However, the callback function is only invoked when the output is available.
Syntax Differences
Based on languages that a user may use, the X DevAPI can implement a function like executeAsync() in altercation for either execute([mysqlx.Async]) or in tallying to execute ([mysqlx.Async]).
For instance, all executions of commands are synchronous when coded in Node.js. Hence, Node.js/Connector does not require differentiating between executeAsync() and execute(). Thus, Node.js/Connector simply applies the execute() that helps to return the objects of JavaScript Promises, which denotes default execution for the MySQL asynchronous.
For example, toughly input programming languages, such as Java, and c#, may benefit from holding two uniquely named API calls for both asynchronous and synchronous executions. But these two calls may take diverse return types. For illustration, the J/Connector can implement execute() to output a RowResult or DocResult and executeAsync() to result in a CompletableFuture<T> where the parameter type is said to be one of the output types.
Also, MySQL 5.7 version maintenances an X plugin or, say, X protocol that permits, if its library supports, asynchronous query command execution. We can also say that we can use this MySQL X plugin or X protocol with Node.js to improve a slow query presentation to have parallel query execution. For this process, we may have to follow the following steps:
- Initially, we will have to allow the X plugin to enable in MySQL 5.7.12+ that will implement a different port where 33060 is the default.
- Next, we will download and set up NodeJS, which is >4.2,,,, and the mysql-connector-nodejs-1.0.2.tar.gz file. You can visit the link Getting Started with Connector/NodeJS for a guide. Remember, for older systems, perhaps you may require to upgrade the nodejs version; take guidance from this link Installing Node.js via the package manager.
- Finally, you have completed all the necessary requirements, and you can now begin exploring the features of asynchronous queries and their execution.
Example of MySQL Asynchronous
Let us view the code part for MySQL Asynchronous using the JavaScript node.js as below:
var book = db.getTable ('Books');
book.select('BookName','Price')
.where('BookName like: bookname')
.orderBy('BookName')
.bind('bookname','e%')
.execute(function (row)) {
// to perform something with a table row
})
.catch(err){
// to handle error
});We will write similar code in other code languages like C# then; Here is an example:
var book = db.GetTable ("Books");
book.select("BookName","Price")
.Where("BookName like: bookname")
.OrderBy("BookName")
.Bind("bookname","e%")
.ExecuteAsync();
Select.ContinueWith(t =>
{
If (t.Exception !=null)
// to handle error
}
// to perform something with the set of result
});Again, let us evaluate the identical code in Java:
Table book = db.getTable ('Books');
// you can run the query asynchronously to get a future
CompletableFuture<RowResult> rowsFuture = book.select ("bookname", "price")
.where('BookName like: bookname')
.orderBy('BookName')
.bind('bookname','e%')
.ExecuteAsync());
// dependent functions can be involved to the CompletableFutureBut writing the above code for MySQL Asynchronous in C++, the asynchronous execution has not been implemented yet in C++/Connector.
Asynchronous operations by using Awaits
Few coding languages can apply an async/await arrangement. So, let us also illustrate some examples of Asynchronous operations by using Awaits,,, explained in detail below:
For code in C#:
Task<RowResult>getBookTask = Books.Select("BookName","Price")
.Where("BookName like: bookname")
.OrderBy("BookName")
.Bind("bookname","e%")
.ExecuteAsync();
// while the getBookTask is running in the background you can perform anything else
//now, here at this period we are up-to-date to receive our outputs back. But if this is not performed then, this will be blocked till done
RowResult rowres = await getBookTask;
Foreach(var row in rowres.FetchAll())
{
// using row object
}Here, Node.js/Connector implements the MySQL asynchronous operations that use Promises applied for all network procedures. Let us see some other specimens:
For code in Java language:
Table book = db.getTable ("Books");
// you can run the query asynchronously to get a future
CompletableFuture<RowResult> rowsFuture = book.select ("bookname", "price")
.where("BookName like: bookname")
.orderBy("BookName")
.bind("bookname","e%")
.ExecuteAsync());
// pause till it is ready
RowResult rows = rowsFuture.get();But writing the above code for MySQL Asynchronous in C++, the asynchronous execution has not been implemented yet in C++/Connector.
Conclusion
- Any MySQL client maintenances the X Protocol, which gives query execution in an asynchronous approach by either using Promises, callbacks,,, or by openly waiting on a definite output at the instant in time when it is truly necessary. It helps with the parallel query execution operations in the server.
- However, the MySQL Shell does not support MySQL asynchronous operations.
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