Application of JDBC in performance test

author ： Huangyandi

Preface

Can we get around  http  agreement , Directly test the performance of the database ？ Do you feel like exporting from the database  CSV  It is very troublesome to construct the pressure measurement data by file ？ How to clean up data after pressure measurement ？ Can I insert into the database （ Delete ） Record assertions made to pressure test requests ？ Use alicloud performance testing tools  PTS  The above problems can be easily solved .

What is?  JDBC

JDBC（Java DataBase Connectivity,Java  Database connection ） It's one for execution  SQL  Of the statement  Java API, It can provide unified access for a variety of relational databases , It's used by a group  Java  Language written classes and interfaces .JDBC  It provides a benchmark , From this, you can build more advanced tools and interfaces , Enable database developers to write database applications .

In short ,JDBC  Do three things ： Establish a connection to the database 、 Send the statement to operate the database and process the result .

JDBC  Design principle of

The overall architecture

JDBC  Developed a set of standards to interact with the database , The database manufacturer provides the implementation of this set of standards , In this way, we can pass the unified  JDBC  Interface to connect various databases . so to speak  JDBC  The function of is to shield the differences between the underlying databases , Make the user follow  JDBC  The code can be executed on various databases . So how does this come true ？ As shown in the figure below ：

JDBC  Defined  Driver  Interface , This interface is the database driver ,  All operations dealing with the database will come down to this in the end  , The database manufacturer must implement this interface , This interface is used to complete the interaction between the caller of the upper application and the underlying concrete database .Driver  It's through  JDBC  Provided  DriverManager  To register , The registration code is written in  Driver  In the static block of , Such as  MySQL  The registration code of is as follows ：

static {
 try {
 java.sql.DriverManager.registerDriver(new Driver());
 } catch (SQLException E) {
 throw new RuntimeException("Can't register driver!");
 }
 }


As a specification for driving definitions  Driver, Its main purpose is to establish a connection with the database , So its interface is also very simple , As shown below ：

public interface Driver {
 // Establishing a connection
 Connection connect(String url, java.util.Properties info)
 throws SQLException;
 boolean acceptsURL(String url) throws SQLException;
 DriverPropertyInfo[] getPropertyInfo(String url, java.util.Properties info)
 throws SQLException;
 int getMajorVersion();
 int getMinorVersion();
 boolean jdbcCompliant();
 public Logger getParentLogger() throws SQLFeatureNotSupportedException;
}


As  Driver  The manager of  DriverManager, It is not only responsible for  Driver  Registration of ／ Cancellation , You can also get the connection directly . How does it do it ？ Look at the following code and find , Actually, it has been registered through traversal  Driver, Find one that can successfully establish a connection  Driver, And will  Connection  return ,DriverManager  Like an agent , The process of establishing the real connection is still left to the specific  Driver.

for(DriverInfo aDriver : registeredDrivers) {
 // If the caller does not have permission to load the driver then
 // skip it.
 if(isDriverAllowed(aDriver.driver, callerCL)) {
 try {
 println(" trying " + aDriver.driver.getClass().getName());
 Connection con = aDriver.driver.connect(url, info);
 if (con != null) {
 // Success!
 println("getConnection returning " + aDriver.driver.getClass().getName());
 return (con);
 }
 } catch (SQLException ex) {
 if (reason == null) {
 reason = ex;
 }
 }

 } else {
 println(" skipping: " + aDriver.getClass().getName());
 }

 }


Connection  Design

From the previous section, we know that the database provider implements Driver Interface to provide services to users ,Driver The core method of the interface is to obtain the connection .Connection It is the core interface for dealing with databases , Let's take a look at its design .

By looking at the design drawings, we find that there are mainly two types of interfaces ：DataSource  and  Connection. Let's introduce them one by one .

• DataSource

Look at the source code directly , As shown below , The core method of discovery is  Driver  equally , It is also to obtain the connection . Then why do we have to  DataSource  Well ？Driver  Isn't it the one that gets the connection ？ Let's take a look  DataSource  How to get the connection .

 public interface DataSource extends CommonDataSource, Wrapper {
 Connection getConnection() throws SQLException;
 Connection getConnection(String username, String password)
 throws SQLException;
}


But we found that  JDBC  It only defines  DataSource  The interface of , There is no specific implementation , So let's do that  Spring  Realized  SimpleDriverDataSource  For example , Let's see how it's done , The code is as follows , Find out  DataSource  Of  getConnection(...) Method , In the end, it was left to  driver.connect(...) To really make a connection . So back to what we described at the beginning , Driver  Is the real interface to deal with the database .

protected Connection getConnectionFromDriver(Properties props) throws SQLException {
 Driver driver = getDriver();
 String url = getUrl();
 Assert.notNull(driver, "Driver must not be null");
 if (logger.isDebugEnabled()) {
 logger.debug("Creating new JDBC Driver Connection to [" + url + "]");
 }
 return driver.connect(url, props);
 }


So here comes the question , Why do we still need  DataSource  Such an interface , Why don't you kill me with one stone ？ Obviously not. .DataSource  It's an enhanced version  Driver. It leaves the core process of establishing connections to  Driver  perform , For creating a cache , Handle distributed transactions, connection pools, and other things that seem unrelated to establishing connections . As shown in the design diagram of the class , With  PTS  The use of  Druid  Take the connection pool as an example ：

• ConnectionPoolDataSource： Implementation of connection pool , This data source implementation does not directly create a physical connection to the database , It's a logical implementation , Its role is to pool database physical connections .

• PooledConnection： coordination  ConnectionPoolDataSource, It gets a pooled object  PooledConnection, And then through the  PooledConnection  Get the physical connection indirectly .

obviously , Through connection pooling, we can get away from the management of connections , Improve connection utilization efficiency , It can also improve the pressure capacity of the press .

Statement  Design

Once the connection is established , Users may want to start writing  SQL  sentence , And it was handed over to the database for execution . These are through  Statement  To achieve . It is mainly divided into ：

• Statement： Define a static  SQL  sentence , The database needs to be recompiled every time it is executed , It is generally used when the query is executed only once and the result is returned .

• PreparedStatement： Define a precompiled with parameters  SQL  sentence , Next execution , It will fetch the statements after times from the cache , Without having to recompile , It is applicable to..., which executes the same logic multiple times  SQL  sentence , Of course, it can also prevent  SQL  Injection and other functions , High security and efficiency , More frequently used . For performance testing , choice  PreparedStatement  Most suitable .

• CallableStatement： Used to call stored procedures .

ResultSet  Design

JDBC  Use  ResultSet  Interface to undertake  Statement  The results of the implementation of .ResultSet  How to use the pointer （next()） To get the search results one by one , When the pointer points to a piece of data , Users can freely choose to obtain the data of a certain column .PTS  By way of  ResultSet  Turn it into  CSV  file , Assist the user with a  SQL  sentence , Construct complex pressure measurement data .

JDBC  Architecture summary

Through the above introduction, we find that ,JDBC  The design of is still hierarchical .

（1）Driver  and  DriverManager  It is database oriented , Designed a set of  Java  Specifications for accessing data , Database vendors only need to implement this set of specifications ;

（2）DataSource  and  Connection  For application developers , They don't care  JDBC  How to interact with the database , Through unified  DataSource  You can get the interface  Connection, Users' data operations can be performed through this  Connection  To implement the ;

（3）Statement  It carries the concrete  SQL  command , Users can define different  Statement  To send instructions to the database ;

（4）ResultSet  Is used to carry  SQL  Command execution results .

thus , It's done   The load driver  ->  Establishing a connection  ->  Carry out orders  ->  Return results   The whole process of interacting with the database . If this process is flexibly embedded in  PTS  In the performance test , The problems mentioned in the preface can be solved .

JDBC  Application in performance testing

Database performance test

• background

Most operations on databases are done through  HTTP、FTP  Or other agreements , But in some cases , It is also meaningful to test the database directly without intermediate protocols . For example, we want not to trigger all related queries , And only test specific  high-value  Query performance ; Verify the performance of the new database under high load .2. Verify some database connection pool parameters , For example, the maximum number of connections   3. Save time and resources . When we want to optimize  SQL  when , Modify the  SQL  Statements and other database operations are tedious , adopt  JDBC  Pressure measurement , We can avoid hacking code , Focus on  SQL  Tuning .

• step

1、 Create a scene . We are  PTS  Console 【 Pressure measuring center 】->【 Create a scene 】 Created in  PTS  Pressure test scenario ;

2、 Scene configuration .PTS  Support for  MySQL、PostgreSQL  And other four databases to initiate pressure test . The user fills in  JDBC URL、 user name 、 Passwords and  SQL  Pressure measurement can be initiated . meanwhile ,PTS  It also supports extraction  ResultSet  The data in is used as the output parameter , To the downstream  API  Use ; Assert the response .

3、 Monitoring and pressure test report during pressure test .PTS  It supports binding to Alibaba cloud  RDS  Cloud resource monitoring , Observe during pressure measurement  RDS  Real time performance index . Besides ,PTS  Clear and complete pressure test reports and sampling logs are also provided , For users to view at any time .

Pressure measurement data structure

• background

Simulate different user login 、 In scenarios such as pressure test business parameter transmission , It is necessary to use the parameter function to realize various dynamic operations in the pressure measurement request . If traditional  CSV  File parameters , Will be limited by file size , And manual creation takes effort . Use  JDBC  To construct pressure measurement data , Can avoid the above problems .

• step

1、 Add data sources . Edit in the scene - Data source management , Select Add  DB  data source , Input  URL、 user name 、 Passwords and  SQL.

2、 Add parameter . Fill in the custom parameter name and column index .

3、 Debugging verification . Click debug scenario , You can verify whether the extracted result set meets the expectations . next , We can use... Wherever we want to use parameters ${} Just quote .

Clean the dirty data of pressure measurement

• background

Pressure test for write request , A lot of dirty data will be generated in the database . How to automatically clean up after pressure measurement ？

• step

PTS  Provides users with solutions .PTS  It supports logical sequencing of serial links , That is, the front link 、 Common link and post link . The order of execution is from first to last . Set a serial link as a post link , Fill in the number of cycles .

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