How do indexing and MapReduce algorithms work?

Question

PHP

Greetings!
I'm interested in any articles that talk about how databases work? What algorithms are used? How does indexing work? How is MapReduce?
I have only superficial knowledge of these algorithms (red-black tree, A*, etc.). I want to understand them in more detail. And for fun and fun, write a document-oriented database in PHP.
For starters, it would be good to read about indexing, and about MapReduce.
Please share links to literature and articles. Thank you.

Answer 1

Start here

Answer 2

Everyone has a different implementation - it depends on the architecture of the cluster, on the data model.
In Couchbase, for example, the user writes the Map, Reduce functions in JavaScript.
In Hadoop, you can write them in Java, C++, and even use third-party executables.
SQL can also be thought of as a kind of Map.
The cluster architecture can change the implementation very much.

And for fun and fun, write a document-oriented database in PHP.

How much time will you waste ...
Better google on the topic "algorithms for storing and sorting data."

Answer 3

Very good example at php sebastian-bergmann.de/archives/750-Map-and-Reduce-in-PHP.html , enjoy the simplicity of the solution :)