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  • Book Overview & Buying Learning PostgreSQL
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Learning PostgreSQL

Learning PostgreSQL

By : Salahaldin Juba, Achim Vannahme, Andrey Volkov
4.3 (6)
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Learning PostgreSQL

Learning PostgreSQL

4.3 (6)
By: Salahaldin Juba, Achim Vannahme, Andrey Volkov

Overview of this book

PostgreSQL is one of the most powerful and easy to use database management systems. It supports the most advanced features included in SQL standards. The book starts with the introduction of relational databases with PostegreSQL. It then moves on to covering data definition language (DDL) with emphasis on PostgreSQL and common DDL commands supported by ANSI SQL. You will then learn the data manipulation language (DML), and advanced topics like locking and multi version concurrency control (MVCC). This will give you a very robust background to tune and troubleshoot your application. The book then covers the implementation of data models in the database such as creating tables, setting up integrity constraints, building indexes, defining views and other schema objects. Next, it will give you an overview about the NoSQL capabilities of PostgreSQL along with Hstore, XML, Json and arrays. Finally by the end of the book, you'll learn to use the JDBC driver and manipulate data objects in the Hibernate framework.
Table of Contents (16 chapters)
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15
Index

Cleaning up data in the database


Cleaning up data is an important topic; often, the data life cycle is not defined when creating a database application. This leads to tons of outdated data. Unclean data hinders several processes, such as database refactoring. Also, it can have a side effect on all processes in the company, such as wrong report results, billing issues, unauthorized access, and so on.

Getting ready

Several recipes were introduced to determine unused objects, but this is not all. The data itself should be cleaned, and the data life cycle should be defined.

For unclean data, there are several scenarios; however, let's focus here only on duplicated rows due to the missing unique and primary key constraints.

How to do it…

The first step is to identify the tables that do not have unique and primary key constraints. This is quite easy using the information schema, as follows:

SELECT table_catalog, table_schema, table_name
FROM
  information_schema.tables
WHERE
  table_schema NOT IN ...
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Learning PostgreSQL
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