https://blog.csdn.net/longshenlmj/article/details/50542683

常见关系型数据库：

1. Oracle
2. MySql
3. Microsoft SQL Server
4. SQLite
5. PostgreSQL
6. IBM DB2

常见的非关系型数据库：

1. 键值数据库：Redis、Memcached、Riak
2. 列族数据库：Bigtable、HBase、Cassandra
3. 文档数据库：MongoDB、CouchDB、MarkLogic
4. 图形数据库：Neo4j、InfoGrid

二者区别

非关系型没有表结构，不支持sql

主键、外键

https://blog.csdn.net/weixin_31642161/article/details/113113942

有可能没有主键

联合主键，复合主键

联合主键：数据库表的主键由两个及以上的字段组成。

复合主键：有争议

1 离线

1.用户行为数据

jar-》log-》flume-》kafka-》flume-》hdfs

用户行为数据存储在日志服务器，以.log文件存在，log-》flume-》kafka-》flume-》hdfs

2 业务数据

jar-》mysql-》sqoop-》hdfs

业务数据存储在mysql，使用sqoop导入hdfs

2 实时

1.用户行为数据

前端-》Nginx-》日志服务器-》）log，Kafka（ods

1 前端埋点数据

通过jar包模拟

2 Nginx

https://blog.csdn.net/qq_40036754/article/details/102463099

负载均衡

3 日志服务器

spring boot搭建

首先，Spring 就是一个java框架，spring boot在 Spring 的基础上演进

4 落盘，整合 Kafka

落盘指的是存在日志服务器

生产者-》kafka-》消费者

​ 生产 消费

2 业务数据

jar-》mysql-》flinkcdc-》kafka（ods）

不能使用sqoop，因为sqoop底层为mapreduce，太慢了，改用canal，maxwell或者flinkcdc

数据从mysql读到kafka，不是hdfs

flink-cdc

https://cloud.tencent.com/developer/article/1801766

Change Data Capture(变更数据获取）

https://www.cnblogs.com/arxive/p/9673830.html

https://blog.panoply.io/how-to-create-a-data-dictionary

https://www.secoda.co/blog/how-to-create-a-data-dictionary-a-step-by-step-guide

https://www.cnblogs.com/schoolbag/p/9759214.html

https://www.cnblogs.com/yjd_hycf_space/p/7772722.html

https://blog.csdn.net/qq_33269009/article/details/90522087

https://blog.csdn.net/Stubborn_Cow/article/details/48420997

注意：很多人理解的ETL是在经过前两个部分之后，加载到数据仓库的数据库中就完事了。ETL不仅仅是在源数据—>ODS这一步，ODS—>DW, DW—>DM包含更为重要和复杂的ETL过程。

1.数据同步策略

1 全量

存储完整的数据。

2 增量

存储新增加的数据。

3 新增及变化

存储新增加的数据和变化的数据。

4 特殊

某些特殊的表，可不必遵循上述同步策略。

1.例如某些不会发生变化的表

地区表，省份表，民族表等，可以只存一份固定值。

2.拉链表

在第一天同步拉链表的时候，需要同步全量数据，并且设置endtime = 9999；首日过后，每日同步数据到拉链表中就是新增及变化的数据，可以采用分区策略，以999为一个分区表示有效的数据，加上以过期时间为分区；

2.首日，每日

首日同步，视情况，不一定全量

每日同步，视情况

https://cwiki.apache.org/confluence/display/hive/design#Design-HiveArchitecture

https://zhuanlan.zhihu.com/p/87545980

https://blog.csdn.net/oTengYue/article/details/91129850

https://jiamaoxiang.top/2020/06/27/Hive%E7%9A%84%E6%9E%B6%E6%9E%84%E5%89%96%E6%9E%90/

https://www.javatpoint.com/hive-architecture

Hive Client

Hive allows writing applications in various languages, including Java, Python, and C++. It supports different types of clients such as:-

• Thrift Server - It is a cross-language service provider platform that serves the request from all those programming languages that supports Thrift.
• JDBC Driver - It is used to establish a connection between hive and Java applications. The JDBC Driver is present in the class org.apache.hadoop.hive.jdbc.HiveDriver.
• ODBC Driver - It allows the applications that support the ODBC protocol to connect to Hive.

Hive Services

The following are the services provided by Hive:-

• Hive CLI - The Hive CLI (Command Line Interface) is a shell where we can execute Hive queries and commands.
• Hive Web User Interface - The Hive Web UI is just an alternative of Hive CLI. It provides a web-based GUI for executing Hive queries and commands.
• Hive MetaStore - It is a central repository that stores all the structure information of various tables and partitions in the warehouse. It also includes metadata of column and its type information, the serializers and deserializers which is used to read and write data and the corresponding HDFS files where the data is stored.
• Hive Server - It is referred to as Apache Thrift Server. It accepts the request from different clients and provides it to Hive Driver.
• Hive Driver - It receives queries from different sources like web UI, CLI, Thrift, and JDBC/ODBC driver. It transfers the queries to the compiler.
• Hive Compiler - The purpose of the compiler is to parse the query and perform semantic analysis on the different query blocks and expressions. It converts HiveQL statements into MapReduce jobs.
• Hive Execution Engine - Optimizer generates the logical plan in the form of DAG of map-reduce tasks and HDFS tasks. In the end, the execution engine executes the incoming tasks in the order of their dependencies.

计算引擎

Hive支持MapReduce、Tez、Spark

https://cloud.tencent.com/developer/article/1893808

https://blog.csdn.net/kwu_ganymede/article/details/52223133

数据存储

https://cloud.tencent.com/developer/article/1411821

Hive是基于hdfs的，它的数据存储在Hadoop分布式文件系统中。Hive本身是没有专门的数据存储格式，也没有为数据建立索引，只需要在创建表的时候告诉Hive数据中的列分隔符和行分隔符，Hive就可以解析数据。

default数据库中的表的存储位置 /user/hive/warehouse
其他数据库的表自己指定

The Challenges of Data Quality and Data Quality Assessment in the Big Data Era

https://pdfs.semanticscholar.org/0fb3/7330a4170ec63d60eec7dbb2b86e6829a3de.pdf

A Data Quality in Use model for Big Data

Automating LargeScale Data Quality Verification

Data Sets and Data Quality in Software Engineering

Discovering Data Quality Rules

Context-aware Data Quality Assessment for Big Data