问题描述和解决过程
在安装好hive后，直接在控制台输入hive，即可启动hive。但输入show databases;出现了关于下列的异常：
FAILED: HiveException java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient；
翻译过来就是hive元数据连接有问题。
然后发现要先安装mysql和mysql的驱动，再配置一个hive-site.xml（在hive安装目录下conf文件夹里有一个模板文件）
然后我安装了mysql5.7
然后下载了mysql的驱动mysql-connector-java-5.1.49.jar,复制mysql的驱动程序到hive/lib下面
然后填写hive-site.xml（注意要填写mysql的地址和用户名和密码，mysql连接地址这里会有坑，后面说）
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<configuration>
<property>
<name>javax.jdo.option.ConnectionURL</name>
<!-- 注意下面这行 会有问题 -->
<value>jdbc:mysql://master:3306/hive?createDatabaseIfNotExist=true&useSSL=false</value>
</property>
<property>
<name>javax.jdo.option.ConnectionDriverName</name>
<value>com.mysql.jdbc.Driver</value>
</property>
<property>
<name>javax.jdo.option.ConnectionUserName</name>
<value>root</value>
</property>
<property>
<name>javax.jdo.option.ConnectionPassword</name>
<value>123456</value>
</property>
<property>
<name>hive.metastore.schema.verification</name>
<value>false</value>
</property>
</configuration>
然后执行schematool -dbType mysql -initSchema就开始报错了！
第一次报错：Communications link failure
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ schematool -dbType mysql -initSchema
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/amax/Downloads/apache-hive-2.3.9-bin/lib/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/hadoop/share/hadoop/common/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Metastore connection URL: jdbc:mysql://master:3306/hive?createDatabaseIfNotExist=true&useSSL=false
Metastore Connection Driver : com.mysql.jdbc.Driver
Metastore connection User: root
org.apache.hadoop.hive.metastore.HiveMetaException: Failed to get schema version.
Underlying cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException : Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
SQL Error code: 0
Use --verbose for detailed stacktrace.
*** schemaTool failed ***
我推测是jdbc那一行的地址有问题，于是修改了hive-site.xml,把master改为我本机ip，发现还是报错：
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ vi hive-site.xml
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ schematool -dbType mysql -initSchema
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/amax/Downloads/apache-hive-2.3.9-bin/lib/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/hadoop/share/hadoop/common/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Metastore connection URL: jdbc:mysql://172.31.58.2:3306/hive?createDatabaseIfNotExist=true&useSSL=false
Metastore Connection Driver : com.mysql.jdbc.Driver
Metastore connection User: root
org.apache.hadoop.hive.metastore.HiveMetaException: Failed to get schema version.
Underlying cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException : Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
SQL Error code: 0
Use --verbose for detailed stacktrace.
*** schemaTool failed ***
然后我查看了3306这个端口，发现有被监听，但写的是127.0.0.1，所以干脆在hive-site.xml中改成127.0.0.1:3306试试，发现这次是另外一个错了not allowed to connect to this MySQL server
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ netstat -an|grep 3306
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ vi hive-site.xml
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ schematool -dbType mysql -initSchema
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/amax/Downloads/apache-hive-2.3.9-bin/lib/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/hadoop/share/hadoop/common/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Metastore connection URL: jdbc:mysql://127.0.0.1:3306/hive?createDatabaseIfNotExist=true&useSSL=false
Metastore Connection Driver : com.mysql.jdbc.Driver
Metastore connection User: root
org.apache.hadoop.hive.metastore.HiveMetaException: Failed to get schema version.
Underlying cause: java.sql.SQLException : null, message from server: "Host '172.31.59.5' is not allowed to connect to this MySQL server"
SQL Error code: 1130
Use --verbose for detailed stacktrace.
*** schemaTool failed ***
估计是权限问题，于是我登录mysql给这个ip授权
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.7.33-0ubuntu0.16.04.1 (Ubuntu)
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> GRANT ALL ON *.* to root@172.31.59.5 IDENTIFIED BY '123456';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> EXIT
Bye
再尝试一次，这回终于成功了！
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ schematool -dbType mysql -initSchema
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/amax/Downloads/apache-hive-2.3.9-bin/lib/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/hadoop/share/hadoop/common/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Metastore connection URL: jdbc:mysql://127.0.0.1:3306/hive?createDatabaseIfNotExist=true&useSSL=false
Metastore Connection Driver : com.mysql.jdbc.Driver
Metastore connection User: root
Starting metastore schema initialization to 2.3.0
Initialization script hive-schema-2.3.0.mysql.sql
Initialization script completed
schemaTool completed
amax@master:~/Downloads/apache-hive-2.3.9-bin/conf$ hive
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/amax/Downloads/apache-hive-2.3.9-bin/lib/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/hadoop/share/hadoop/common/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Logging initialized using configuration in jar:file:/home/amax/Downloads/apache-hive-2.3.9-bin/lib/hive-common-2.3.9.jar!/hive-log4j2.properties Async: true
Hive-on-MR is deprecated in Hive 2 and may not be available in the future versions. Consider using a different execution engine (i.e. spark, tez) or using Hive 1.X releases.
hive (default)> show databases;
OK
database_name
default
Time taken: 5.296 seconds, Fetched: 1 row(s)
