Intro to Databases

Intro to Databases is a 1 hour introduction, with live coding examples, about databases to undergraduate students.

1. Databases! Preetam Jinka March 2014 Intro to
2. Me. 2nd year math major Twitter/GitHub: @PreetamJinka Website: http://preet.am/ Email: preetam@virginia.edu Credit: Yugank Singhal
3. Code along! https://github.com/PreetamJinka/intro-to-databases 1. Get Node.js 2. Clone the repository 3. Run npm install
4. Disclaimers. • Limited scope • Alternatives used
5. Ask questions!
6. What the heck is a database? <math-mode> DEFINITION.
7. What the heck is a database?
8. Database Management Systems Systems that manage organized collections of data. From now on: “database” ⇒ DBMS
9. There are tons of databases out there. What sets them apart?
10. 1. The structure of data. - How does the database look at data? 2. The questions you can ask. - Queries
11. Types • Relational ◦ MySQL, PostgreSQL, Oracle, … • Document stores ◦ MongoDB, CouchDB, Couchbase, … • Graph ◦ Neo4j, … • Key-value stores ◦ File system, Redis, FoundationDB, … • Search ◦ Lucene, Solr, Elasticsearch, … … and a bunch of others I’m missing.
12. Types • Relational ◦ MySQL, PostgreSQL, Oracle, … • Document stores ◦ MongoDB, CouchDB, Couchbase, … • Graph ◦ Neo4j, … • Key-value stores ◦ File system, Redis, FoundationDB, … • Search ◦ Lucene, Solr, Elasticsearch, … … and a bunch of others I’m missing.
13. Key-value stores Like associative arrays, dictionaries, maps, hashes, … key value "2+2" 4 1 true "foo" "bar"
15. File systems! key value /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 127.0.1.1 .gitignore ## .gitignore ## # dependencies node_modules/ # secret tokens tokens.js
16. Demo!
17. Redis A really fast advanced key-value store. “Data structure server” strings, hashes, lists, sets and sorted sets
18. Querying Redis
19. Relational databases Think “tables” By “relational,” we mean having to do with relations.
20. Relational databases username first name last name bob Bob Barker alice Alice Cooper pj Preetam Jinka Languages table username language bob JavaScript alice C++ pj Go Users table
21. Relational databases username first name last name bob Bob Barker alice Alice Cooper pj Preetam Jinka Languages table username language bob JavaScript alice C++ pj Go Users table Relation!
22. SQL Structured Query Language This is how we interact with most, if not all, relational databases.
23. Demo!
24. Document databases Type of key-value stores. Values are “documents”
25. Example document { "_id": "post_1", "title": "Hello, world", "content": "This is my first blog post!", "tags": ["general"] } post_1 is the “key”
26. MongoDB’s collections Collections are groups of documents. They’re like tables in MongoDB’s context.
27. Document database queries • Get individual documents • Find documents that ◦ have a certain value ◦ have properties that… ▪ have a certain value
28. Demo!
29. Map-reduce Source: http://docs.mongodb.org/manual/core/map-reduce/
30. Map-reduce
31. Demo!
32. IMPORTANT: There’s no one database to rule them all. Unfortunate. :-/
33. Use the right tool for the job.
34. You wouldn’t use a hash table for an ordered map, right? Please say yes :P
35. Case study
36. The application and the database Application Application Application Database State State State “stateless web application are far more flexible and scalable than their stateful counterparts” — Application State - We all want to be Stateless
37. Database State State State web_app( ) State Web page
38. Twelve-Factor App Methodology 12factor.net “Twelve-factor processes are stateless and share-nothing. Any data that needs to persist must be stored in a stateful backing service, typically a database.”
39. Dude, where’s my state?
40. In the database(s).
41. Pro tips Write abstractions. Keep things simple. Mock and test.
42. Pro tips Ask for help.
43. That’s all (for now), folks! Thanks for coming! @PreetamJinka preetam@virginia.edu