Book Image

Mastering PostgreSQL 9.6

By : Hans-Jürgen Schönig
Book Image

Mastering PostgreSQL 9.6

By: Hans-Jürgen Schönig

Overview of this book

PostgreSQL is an open source database used for handling large datasets (Big Data) and as a JSON document database. It also has applications in the software and web domains. This book will enable you to build better PostgreSQL applications and administer databases more efficiently. We begin by explaining the advanced database design concepts in PostgreSQL 9.6, along with indexing and query optimization. You will also see how to work with event triggers and perform concurrent transactions and table partitioning, along with exploring SQL and server tuning. We will walk you through implementing advanced administrative tasks such as server maintenance and monitoring, replication, recovery and high availability, and much more. You will understand the common and not-so-common troubleshooting problems and how you can overcome them. By the end of this book, you will have an expert-level command of the advanced database functionalities and will be able to implement advanced administrative tasks with PostgreSQL.
Table of Contents (14 chapters)
Free Chapter
1
PostgreSQL Overview

Inspecting the log

If your system smells trouble, it makes sense to inspect the log to see what is going on. The important point is this: not all log entries are created equal. PostgreSQL has a hierarchy of log entries that ranges from DEBUG messages to PANIC.

To the administrator, the following three error levels are of great importance:

  • ERROR
  • FATAL
  • PANIC

ERROR is used for problems such as syntax errors, permission-related problems, and so on. Your log will always contain error messages. The critical factor is: how often does a certain type of error show up? Producing millions of syntax errors is certainly not the ideal strategy to run a database server.

FATAL is more scary than ERROR; you will see messages such as could not allocate memory for shared memory name or unexpected walreceiver state. In other words, those error messages are already really scary and will tell you that things are going wrong.

Finally...