Tài liệu Seven Databases in Seven Weeks pptx

[...]... rows Join Reads All of the other databases we’ll read about in this book perform CRUD operations as well What sets relational databases like PostgreSQL apart is their ability to join tables together when reading them Joining, in essence, is an operation taking two separate tables and combining them in some way to return a single table It’s somewhat like shuffling up Scrabble pieces from existing words... where other databases often fall flat is crawling through selfreferential or otherwise intricately linked data This is exactly where Neo4J shines The benefit of using a graph database is the ability to quickly traverse nodes and relationships to find relevant data Often found in social networking applications, graph databases are gaining traction for their flexibility, with Neo4j as a pinnacle implementation... of Seven Databases in Seven Weeks is this: what database or combination of databases best resolves your problem? If you walk away understanding how to make that choice, given your particular needs and resources at hand, we’re happy But to answer that question, you’ll need to understand your options For that, we’ll take you on a deep dive into each of seven databases, uncovering the good parts and pointing... pack in more useful examples and a discussion of concepts, which is what you really want anyway, right? Administration Manual? We Think Not Along the same lines of installation, this book will not cover everything you’d find in an administration manual Each of these databases has myriad options, settings, switches, and configuration details, most of which are well documented on the Web We’re more interested... as an administrator and by dollar sign as a regular user The shell also comes equipped with the best built -in documentation you will find in any console Typing \h lists information about SQL commands, and \? helps with psql-specific commands, namely, those that begin with a backslash You can find usage details about each SQL command in the following way: book=# \h CREATE INDEX Command: CREATE INDEX Description:... countries table by inserting a few rows INSERT INTO countries (country_code, country_name) VALUES ('us','United States'), ('mx','Mexico'), ('au','Australia'), ('gb','United Kingdom'), ('de','Germany'), ('ll','Loompaland'); Let’s test our unique constraint Attempting to add a duplicate country_name will cause our unique constraint to fail, thus disallowing insertion Constraints are how relational databases like... Seven Weeks: A Pragmatic Guide to Learning Programming Languages [Tat10], we knew he was onto something The progressive style of introducing languages struck a chord with us We felt teaching databases in the same manner would provide a smooth medium for tackling some of these tough NoSQL questions What’s in This Book This book is aimed at experienced developers who want a well-rounded understanding of... degree of flexibility, allowing for variable domains The system imposes few restrictions on incoming data, as long as it meets the basic requirement of being expressible as a document Different document databases take different approaches with respect to indexing, ad hoc querying, replication, consistency, and other design decisions Choosing wisely between them requires understanding these differences and... what these databases have to offer, you have to spend some time using them, and that means rolling up your sleeves and doing some work Although you may be tempted to skip chapters, we designed this book to be read linearly Some concepts, such as mapreduce, are introduced in depth in earlier chapters and then skimmed over in later ones The goal of this book is to attain a solid understanding of the... to the website for installation instructions.2 Once you have Postgres installed, create a schema called book using the following command: $ createdb book We’ll be using the book schema for the remainder of this chapter Next, run the following command to ensure your contrib packages have been installed correctly: $ psql book -c "SELECT '1'::cube;" Seek out the online docs for more information if you . years at IBM Austin working on databases with our labs and customers, this development is simply stunning to me. In Seven Databases in Seven Weeks, you’ll. where your industry is moving and learn the forces driving it there. Enjoy the ride. Bruce Tate author of Seven Languages in Seven Weeks Austin, Texas,