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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

Window functions


Apart from grouping and aggregation, PostgreSQL provides another way to perform computations based on the values of several records. It can be done by using the window functions. Grouping and aggregation implies the output of a single record for every group of input records. Window functions can do similar things, but they are executed for every record, and the number of records in the output and the input is the same:

GROUP BY and Window functions

In the preceding diagram, the rectangles represent the records of a table. Let's assume that the color of the rectangles indicates the value of a field, used to group the records. When GROUP BY is used in a query, each distinct value of that field will create a group, and each group will become a single record in the results of the query. That was explained in Chapter 5, SQL Language. Window functions can access the values of other records of the same group (which is called a partition in this case), although the number of records...

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Learning PostgreSQL
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