某次在内网（无互联网访问），centos7.3 tomcat7部署boot war包是发现，应用每次卡在：[ restartedMain] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.PostgreSQLDialect，时长达10多分钟，使用idea启动boot内嵌tomcat启动时打印如下：
2018-11-27 10:58:39.542 INFO 10488 --- [ restartedMain] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.PostgreSQLDialect
2018-11-27 10:58:47.689 INFO 10488 --- [ restartedMain] o.h.e.j.e.i.LobCreatorBuilderImpl : HHH000424: Disabling contextual LOB creation as createClob() method threw error : java.lang.reflect.InvocationTargetException
研究发现，boot-start包内部嵌套了hibernate，Hibernate默认是使用jdbc方式来取的，而工程使用的是mybatis+druid方式，jdbc自然获取不到连接；通过在application.properties配置：spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults = false即可跳过jdbc hibernate连接，测试验证后再linux环境下启动无卡顿；
boot简单灵活性建立在封装了多种常用组件基础之上，例如hibernate jpa核心服务，该问题切入点可以查看
package org.hibernate.engine.jdbc.env.internal;
...
public class JdbcEnvironmentInitiator implements StandardServiceInitiator<JdbcEnvironment> {
@Override
public JdbcEnvironment initiateService(Map configurationValues, ServiceRegistryImplementor registry) {
final DialectFactory dialectFactory = registry.getService( DialectFactory.class );
// 'hibernate.temp.use_jdbc_metadata_defaults' is a temporary magic value.
// The need for it is intended to be alleviated with future development, thus it is
// not defined as an Environment constant...
//
// it is used to control whether we should consult the JDBC metadata to determine
// certain Settings default values; it is useful to *not* do this when the database
// may not be available (mainly in tools usage).
boolean useJdbcMetadata = ConfigurationHelper.getBoolean(
"hibernate.temp.use_jdbc_metadata_defaults",
configurationValues,
true
);
...
相关调用链分析可以提供IDE分析即可；
也可以通过springboot删除hibernate服务：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
<!--排除Hibernate相关依赖-->
<exclusions>
<exclusion>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
</exclusion>
<exclusion>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
</exclusion>
</exclusions>
</dependency>