Last time we installed the KingbaseES database via Docker, and today we're going to start learning and getting up to speed with KSQL, which is essentially a client-side tool for interacting with the database. Once launched, we can perform queries and operations as if we were using regular SQL, which will be a good opportunity to practice.
It is also an opportunity to explore whether KSQL has any special features or ways of using it, and to see how it differs from traditional SQL tools.
Ksql Quick Start
Connecting to the target database
Using Commandsksql -p 54321 -d testYou'll be able to go directly to the file calledtest of the database. By changing the database name parameter in the command, you can easily switch and enter any other database by simply replacing the-d The database name at the end is sufficient. This approach is very flexible and convenient for users to quickly switch and operate between multiple databases.
basic command
tabulate
Here we are using the standard table creation statement, and the process of creating a table is exactly the same as traditional SQL syntax.
create table todo_info(
id number primary key,
todo_info varchar(1000) not null,
todo_Date date not null,
done boolean not null default false
)
View Table Structure
Ksql also has commands to view the table structure as follows:\d todo_info
variant
KSQL supports the dynamic addition of variables during a session, using a Key-Value structure. This means that users can define and modify variables during a session and use them flexibly in queries and operations.
\set flag Love to eat
\echo :flag
Of course, this does not only include regular variables, but also applies to variables in SQL statements. Next, we'll demonstrate exactly how to use these variables in SQL operations.
insert into todo_info(id,todo_info,todo_date) values(1,:'flag',sysdate);
The use of variables can significantly save you from wasting time writing repetitive code or values. By using variables, you are able to avoid redundant operations and greatly improve development efficiency.
SQL script
KSQL also supports executing SQL scripts, which is one of its powerful features. Next, we will test it with a real-world example. First, we need to enter the Docker container environment and make sure that we edit a test script in the current user's working directory.
Note that you can also edit and use your own SQL scripts as needed. To help you get started quickly, shown below is the content of a simple test script:
CREATE TABLE t1
(
a int,
b int
);INSERT INTO t1 VALUES(1,1);
INSERT INTO t1 VALUES(2,2);SELECT * FROM t1;
After saving, we can execute the command directly from within the Ksql window:\i
This is also a handy command for developers.
Generate HTML
We can convert the results obtained from the query to HTML format for better visualization. Considering that your database tool cannot connect directly to the production database, and the administrative privileges of the production database are usually limited to the DBA (database administrator), you can ask the DBA to export the query results as an HTML file for us to view.
This not only allows for visualization of the data, but also allows for more intuitive analysis and presentation of the results. We may want to try this approach.
\H
After executing the command, let's look at the query results.
The browser can be opened and viewed directly.
Remember to run this command if you want to restore back:\a
Statistics of SQL execution time
In the production environment, SQL execution time is one of the most commonly used performance monitoring metrics, through which we can quickly identify whether there is a potential pitfall of slow queries. Especially when launching new versions or features, analyzing SQL execution time can help us find performance problems in time and avoid negative impact on system responsiveness and stability.
Next, we will take a look at how to enable this monitoring feature.
\timing on
Open it successfully so that you can hide the hidden danger of slow queries directly before you go live.
implementation plan
Another optimization tool that is indispensable in a production environment is the execution plan. Execution plans can reveal whether SQL queries are effectively utilizing indexes during execution, especially when a new table is first launched, and although the SQL execution time is short, as the data volume grows and the query frequency increases, the problem may be gradually exposed.
Therefore, analyzing potential performance bottlenecks through the execution plan in advance can effectively avoid query performance degradation at a later stage. Next, let's try how to view and analyze the execution plan.
explain sql；
This is the expected execution plan. If you wish to see the real results of the actual execution process, you can use the following commands to get a more detailed analysis of the execution and performance.
explain analyze sql；
This command, if you want to execute it, remember to turn on transactions before executing it to ensure that there are no actual modifications or impacts on the database during the test. After execution, be sure to roll back the transaction to restore the data to its original state so as to avoid any unforeseen changes or damage to the database environment.
Exit Ksql
If you need to exit the Ksql command line, type \q.
summarize
Through today's study, we have gained an initial understanding of the KSQL tool and mastered the basic operation skills. We have gradually familiarized ourselves with the powerful features of KSQL, from connecting to databases and creating table structures to executing SQL scripts, to making flexible use of variables and performing performance optimization. Compared with traditional SQL tools, KSQL provides a more efficient workflow, especially when dealing with database queries and debugging, and the flexible command line operations and visualization features save developers a lot of time and effort.
In addition, KSQL supports real-time execution of SQL queries and generation of HTML-formatted results, which greatly facilitates data visualization. By introducing execution plan and SQL execution time monitoring, we can identify potential performance issues and ensure system stability in production environments.
In conclusion, KSQL is a powerful and easy-to-use database client tool, especially for developers and database administrators who need to interact with databases frequently. We hope that through today's practice, you can better master KSQL and apply it to real projects to improve work efficiency and system performance.
I'm Rain, a Java server-side coder, studying the mysteries of AI technology. I love technical communication and sharing, and I am passionate about open source community. I am also a Tencent Cloud Creative Star, Ali Cloud Expert Blogger, Huawei Cloud Enjoyment Expert, and Nuggets Excellent Author.
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