前言
数据胡越来越热门，我也开始探索数据湖在公司落地，把数据湖实践入门、填坑做个记录，也方便以后大家入门
一、数据湖iceberg实践环境说明
1.hadoop版本 社区版 2.7.2
2. hive版本 2.3.6
3. flink版本1.11.6 目前flink出来flink1.14.2，但先选择flink1.11看看，原因是官网建议用flink1.11，减少用其他版本造成的坑。
官网说明： Step.1 Downloading the flink 1.11.x binary package from the apache flink download page. We now use scala 2.12 to archive the apache iceberg-flink-runtime jar, so it’s recommended to use flink 1.11 bundled with scala 2.12.
二、启动flink sql客户端
1. 启动flink standalone集群
https://iceberg.apache.org/#flink/#preparation-when-using-flink-sql-client
代码如下（示例）：
# HADOOP_HOME is your hadoop root directory after unpack the binary package.
export HADOOP_CLASSPATH=`$HADOOP_HOME/bin/hadoop classpath`
# Start the flink standalone cluster
./bin/start-cluster.sh2.下载flink iceberg runtime的包，启动flink-sql
代码如下（示例）：
下载地址：https://repo.maven.apache.org/maven2/org/apache/iceberg/iceberg-flink-runtime/
iceberg-flink-runtime-xxx.jar
我使用 iceberg-flink-runtime-0.11.1.jar
启动flink sql并带上iceberg
bin/sql-client.sh embedded -j /opt/software/iceberg-flink-runtime-0.11.1.jar shell3.创建基于hadoop的catalog
创建脚本，warehouse的路径，它会自动创建
hdfs路径里面 ns是命名空间，但namenode的使用ip:port代替
在flink-sql client 中执行脚本
CREATE CATALOG hadoop_catalog WITH (
'type'='iceberg',
'catalog-type'='hadoop',
'warehouse'='hdfs://ns/user/hive/warehouse/iceberg_hadoop_catalog',
'property-version'='1'
);会自动创建路径 /user/hive/warehouse/iceberg_hadoop_catalog/default， 下面是空的
[root@hadoop101 ~]# hadoop fs -ls /user/hive/warehouse/iceberg_hadoop_catalog/default
Flink SQL> show catalogs;
default_catalog
hadoop_catalog创建数据库
Flink SQL> create database iceberg_db;
[INFO] Database has been created.
Flink SQL> show databases;
default_database
iceberg_db创建表
Flink SQL> CREATE TABLE `hadoop_catalog`.`default`.`sample` (
> id BIGINT COMMENT 'unique id',
> data STRING
> );
[INFO] Table has been created.查看表, 发现从目前库找，找不到。
Flink SQL> use default_database;
Flink SQL> show tables;
[INFO] Result was empty.
Flink SQL> use iceberg_db;
Flink SQL> show tables;
[INFO] Result was empty.从hdfs路径去找，发现，生成了表的目录和元信息
4.写数据，读数据测试（hadoop catalog的限制）
hadoop catalog 创建的东西只能在本客户端使用
打开另一个sql客户端，写数据
bin/sql-client.sh embedded -j /opt/software/iceberg-flink-runtime-0.11.1.jar shell
Flink SQL> INSERT INTO `hadoop_catalog`.`default`.`sample` VALUES (1, 'a');
[INFO] Submitting SQL update statement to the cluster...
[ERROR] Could not execute SQL statement. Reason:
org.apache.flink.table.api.TableException: Sink `hadoop_catalog`.`default`.`sample` does not exists
Flink SQL> show databases;
default_database发现在第一个客户端创建的database和表，都没有， 我先认为这个hadoop catalog的限制。
步骤1： 把所有sql-client的客户端退出，重新进入sql-client
步骤2：检查hadoop上hadoop_catalog对应的表是否还在，发现表还在
发现1. 之前创建的database没有了，获取hadoop_catalog ,
结论： 客户端退出后，catalog在hadoop上的信息还在，但客户端需要重新建立catalog,catalog下的表不用重新建
Flink SQL> show catalogs;
default_catalog
重新创建catalog
Flink SQL> CREATE CATALOG hadoop_catalog WITH (
> 'type'='iceberg',
> 'catalog-type'='hadoop',
> 'warehouse'='hdfs://ns/user/hive/warehouse/iceberg_hadoop_catalog',
> 'property-version'='1'
> );
[INFO] Catalog has been created.
Flink SQL> use hadoop_catalog;
[ERROR] Could not execute SQL statement. Reason:
org.apache.flink.table.catalog.exceptions.CatalogException: A database with name [hadoop_catalog] does not exist in the catalog: [default_catalog].
Flink SQL> use catalog hadoop_catalog;
Flink SQL> show tables;
sample
sample_like
Flink SQL> show databases;
default
Flink SQL> show catalogs;
default_catalog
hadoop_catalog插入两条数据，再查询出来看看
Flink SQL> INSERT INTO `hadoop_catalog`.`default`.`sample` VALUES (1, 'a');
[INFO] Submitting SQL update statement to the cluster...
[INFO] Table update statement has been successfully submitted to the cluster:
Job ID: a7008acfe1389133c1ae6a5c00e4d611
Flink SQL> INSERT INTO `hadoop_catalog`.`default`.`sample` VALUES (2, 'b');
[INFO] Submitting SQL update statement to the cluster...
[INFO] Table update statement has been successfully submitted to the cluster:
Job ID: f642dd21e493d630824cb9b30098de3c
Flink SQL> select * from sample;查询结果：
看看hdfs上的文件
查看data的数据： 发现 2个数据文件
查看metadata，发现metadata比较多
之前没完整记录第一执行后的metadata信息，需要重跑，这个流程，记录完整变更的信息
5.创建基于hive的catalog
5.1 创建hive的catalog失败
创建报错，错误原因，如下图, 没有hive的依赖
建hive catalog语法
CREATE CATALOG hive_catalog WITH (
'type'='iceberg',
'catalog-type'='hive',
'uri'='thrift://hadoop101:9083',
'clients'='5',
'property-version'='1',
'warehouse'='/user/hive/warehouse'
);Flink SQL> CREATE CATALOG hive_catalog WITH (
> 'type'='iceberg',
> 'catalog-type'='hive',
> 'uri'='thrift://hadoop101:9083',
> 'clients'='5',
> 'property-version'='1',
> 'warehouse'='/user/hive/warehouse'
> );
>
Exception in thread "main" org.apache.flink.table.client.SqlClientException: Unexpected exception. This is a bug. Please consider filing an issue.
at org.apache.flink.table.client.SqlClient.main(SqlClient.java:222)
Caused by: java.lang.NoClassDefFoundError: org/apache/hadoop/hive/metastore/api/NoSuchObjectException
at org.apache.iceberg.flink.CatalogLoader$HiveCatalogLoader.loadCatalog(CatalogLoader.java:112)
at org.apache.iceberg.flink.FlinkCatalog.<init>(FlinkCatalog.java:111)
at org.apache.iceberg.flink.FlinkCatalogFactory.createCatalog(FlinkCatalogFactory.java:127)
at org.apache.iceberg.flink.FlinkCatalogFactory.createCatalog(FlinkCatalogFactory.java:117)
at org.apache.flink.table.api.internal.TableEnvironmentImpl.createCatalog(TableEnvironmentImpl.java:1110)
at org.apache.flink.table.api.internal.TableEnvironmentImpl.executeOperation(TableEnvironmentImpl.java:1043)
at org.apache.flink.table.api.internal.TableEnvironmentImpl.executeSql(TableEnvironmentImpl.java:693)
at org.apache.flink.table.client.gateway.local.LocalExecutor.lambda$executeSql$7(LocalExecutor.java:366)
at org.apache.flink.table.client.gateway.local.ExecutionContext.wrapClassLoader(ExecutionContext.java:254)
at org.apache.flink.table.client.gateway.local.LocalExecutor.executeSql(LocalExecutor.java:366)
at org.apache.flink.table.client.cli.CliClient.callDdl(CliClient.java:651)
at org.apache.flink.table.client.cli.CliClient.callDdl(CliClient.java:646)
at org.apache.flink.table.client.cli.CliClient.callCommand(CliClient.java:362)
at java.util.Optional.ifPresent(Optional.java:159)
at org.apache.flink.table.client.cli.CliClient.open(CliClient.java:210)
at org.apache.flink.table.client.SqlClient.openCli(SqlClient.java:147)
at org.apache.flink.table.client.SqlClient.start(SqlClient.java:115)
at org.apache.flink.table.client.SqlClient.main(SqlClient.java:208)
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.hive.metastore.api.NoSuchObjectException
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at org.apache.flink.util.FlinkUserCodeClassLoader.loadClassWithoutExceptionHandling(FlinkUserCodeClassLoader.java:62)
at org.apache.flink.util.ChildFirstClassLoader.loadClassWithoutExceptionHandling(ChildFirstClassLoader.java:65)
at org.apache.flink.util.FlinkUserCodeClassLoader.loadClass(FlinkUserCodeClassLoader.java:47)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 18 more
Shutting down the session...
done.
);解决方法： 增加hive的classpath 看看, 官网没看到增加的方法。。。
想到个办法：直接把hive/lib的classpath放到hadoop classpath上，不就ok了？
export HADOOP_CLASSPATH=`$HADOOP_HOME/bin/hadoop classpath`:/opt/module/hive/lib/*.jar改完，重跑，没效果
继续努力
解决问题思路，
分析问题： 安装报错提示， 是包没找到，由这一行发出来的
org.apache.iceberg.flink.CatalogLoader$HiveCatalogLoader.loadCatalog(CatalogLoader.java:112)
把iceberg的源码下载回来对于0.11分支的。 发现对于的hive是2.3.7版本，跟我使用的hive2.3.6没大版本变动。
解决方法：排除了hive版本问题，hive的classpath也引进来了，继续看官网
最后解决方法：增加flink-sql-connector-hive-2.3.6_2.11-1.11.0.jar
[root@hadoop101 software]# bin/sql-client.sh embedded -j /opt/software/iceberg-flink-runtime-0.11.1.jar -j /opt/software/flink-sql-connector-hive-2.3.6_2.11-1.11.0.jar shell5.1 成功创建catalog
[root@hadoop101 software]# sql-client.sh embedded -j /opt/software/iceberg-flink-runtime-0.11.1.jar -j /opt/software/flink-sql-connector-hive-2.3.6_2.11-1.11.0.jar shell
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/opt/module/flink-1.11.6/lib/log4j-slf4j-impl-2.16.0.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/opt/module/hadoop-2.7.2/share/hadoop/common/lib/slf4j-log4j12-1.7.10.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]
No default environment specified.
Searching for '/opt/module/flink-1.11.6/conf/sql-client-defaults.yaml'...found.
Reading default environment from: file:/opt/module/flink-1.11.6/conf/sql-client-defaults.yaml
No session environment specified.
Command history file path: /root/.flink-sql-history
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|_| |_|_|_| |_|_|\_\ |_____/ \___\_\______| \_____|_|_|\___|_| |_|\__|
Welcome! Enter 'HELP;' to list all available commands. 'QUIT;' to exit.
Flink SQL> CREATE CATALOG hive_catalog WITH (
> 'type'='iceberg',
> 'catalog-type'='hive',
> 'uri'='thrift://hadoop101:9083',
> 'clients'='5',
> 'property-version'='1',
> 'hive-conf-dir'='/opt/module/hive/conf'
> );
2022-01-13 10:58:27,528 INFO org.apache.hadoop.hive.conf.HiveConf [] - Found configuration file null
2022-01-13 10:58:27,741 WARN org.apache.hadoop.hive.conf.HiveConf [] - HiveConf of name hive.metastore.event.db.notification.api.auth does not exist
[INFO] Catalog has been created.5.3 测试基于hive 的catalog对多客户端的支持
在本客户端查看
Flink SQL> show catalogs;
default_catalog
hive_catalog新开一个客户端，（第一个客户端没有退出）
Flink SQL> show catalogs;
default_catalog
Flink SQL> show databases;
default_database结论： 没有看到hive_catalog, 说明： 对hadoop,hive的catalog， 不同客户端是不共享的。
总结
按照官网跑： [link](https://iceberg.apache.org/#flink/).1.了解iceberg 支持3种catalog保存机制
2.目前实践了第一种 保存到hadoop上，这种方式，多客户端无法共享catalog，无法上生产
3.需要使用基于hive的catalog