Spring Boot 2. Hikari Connection Pool optimization

Question

I have a SpringBoot app, I was making some performance test in the controller, and I realized that whatever is the first query I put the controller, It take ages compare to the others... (ths DB is a remote connection, but I can't change this)

long t1 = System.nanoTime();

menuPriceSummaryService.findAllVegan().stream();            

long t2 = System.nanoTime();
long elapsedTimeInSeconds = (t2 - t1) / 1000000000;
System.out.println("elapsedTimeInSeconds1 -> " +  elapsedTimeInSeconds);

t1 = System.nanoTime();

menuPriceSummaryService.findAllVegan();

t2 = System.nanoTime();
elapsedTimeInSeconds = (t2 - t1) / 1000000000;
System.out.println("elapsedTimeInSeconds2 -> " +  elapsedTimeInSeconds);

t1 = System.nanoTime();
menuPriceSummaryService.findAllVegan().parallelStream();
t2 = System.nanoTime();
elapsedTimeInSeconds = (t2 - t1) / 1000000000;
System.out.println("elapsedTimeInSeconds3 -> " +  elapsedTimeInSeconds);

t1 = System.nanoTime();
menuPriceSummaryService.findAllVegan().parallelStream().filter(this::notInMyFavourites);
t2 = System.nanoTime();
elapsedTimeInSeconds = (t2 - t1) / 1000000000;

the time:

elapsedTimeInSeconds1 -> 76
elapsedTimeInSeconds2 -> 0
elapsedTimeInSeconds3 -> 0
elapsedTimeInSeconds4 -> 0

Is it normal? Is there is something I can do configuring the Hikari pool to optimize this?

the pom.xml

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>

the application.properties:

spring.datasource.url=jdbc:mysql://elcordelaciutat.awob1oxhu1so.eu-central-1.rds.amazonaws.com:3306/elcor
spring.datasource.username=elcor
spring.datasource.password=elcor2#$

spring.jpa.show-sql=false
spring.jpa.properties.hibernate.format_sql=true
hibernate.dialect=org.hibernate.dialect.MySQLDialect

Answer 1

You should follow Hikari's MySQL Configuration:

A typical MySQL configuration for HikariCP might look something like this:

dataSource.cachePrepStmts=true
dataSource.prepStmtCacheSize=250
dataSource.prepStmtCacheSqlLimit=2048
dataSource.useServerPrepStmts=true
dataSource.useLocalSessionState=true
dataSource.useLocalTransactionState=true
dataSource.rewriteBatchedStatements=true
dataSource.cacheResultSetMetadata=true
dataSource.cacheServerConfiguration=true
dataSource.elideSetAutoCommits=true
dataSource.maintainTimeStats=false