Models & Intro to DB Architectures

Transcription

1 class 3 Models & Intro to DB Architectures prof. Stratos Idreos

2 welcome brave cs165 students! Stratos Idreos 2 /49

3 NO LAPTOP/PHONE POLICY class is based on participation! we will bring a copy of the slides for every one in each time class so you can follow and keep notes + there is enough evidence that laptops and phones slow you down (check syllabus for more info) Stratos Idreos 3 /49

4 applications sql database kernel algorithms/operators cpu memory data data data disk Stratos Idreos 4 /49

5 a simple example assume an array of N integers: find all positions where value>x qualifying positions select operator exists in all systems: sql, nosql, newsql data even the simplest tasks are actually far from trivial no obvious solutions; just a taste of what to come Stratos Idreos 5 /49

6 what we will do design data structures and algorithms = access methods study design tradeoffs with respect to modern hardware application requirements & complete system design next couple of weeks very basics of data models and languages (today) basics of db architectures (today next couple of classes) column-stores and hardware-conscious designs Stratos Idreos 6 /49

7 Stratos Idreos 7 /49

8 for project: install MonetDB & PostgreSQL/MySQL and play with SQL explain + SQL query to see query plans in MonetDB (use read-only mode) repeat throughout the semester compare with your system in terms of performance this is part of final deliverable & several logistics and tools (code.seas, gdb, perf, valgrind, testing infrastructure) do not underestimate this Stratos Idreos 8 /49

9 what should I be doing? do P0 register to Piazza and stay logged in check syllabus/website carefully check project timeline and plan around it keep up with reading (goes fast) register for notes today (tmr we will do assignments) come to Labs and OH frequently Stratos Idreos 9 /49

10 how to read research papers 1) abstract-intro-related work-conclusions what is the problem why is it important why past solutions do not work what is the core idea what is success 2) core part-analysis basic idea what matters any gaps? 3) follow a few citations and repeat goal: by the end of the semester understand these papers fully Stratos Idreos 10/49

11 we want you to have fun! data systems is an exciting field! tell us how you are keeping up tell us what you need to better follow the class tell us your suggestions about how to improve the class Stratos Idreos 11/49

12 photo of Anand here the evolution of data-driven applications Anand Rajaraman (3) use social data (social networks) use own data (1) (recommendations) (2) use public data (search) (4) all of the above (all of the above) (5) training data (machine learning) Stratos Idreos 12/49

13 food for (big data-driven) thought Anand Rajaraman amazon google Cyborg the cyborg knows & manages all your models linkedin bank X Stratos Idreos 13/49

14 food for (big data-driven) thought the biggest transportations companies have no cars the biggest data companies have no data the biggest hotel companies have no hotels more about this and other thoughts in our first brainstorming session (TBA) Stratos Idreos 14/49

15 logical design physical design system design Stratos Idreos 15/49

16 essential steps in using a database system experts/system admins clean schema load tune query user/apps Stratos Idreos 16/49

17 relational model+sql database professors (id,name, ) key table/relation courses (id,name, profid, ) column/attribute students (id,name, ) create table for professors: create table professors (id:integer, name: char(40), telephone: char(10), ) insert into professors ( , john smith, ) give me the names of all students: select name from students where GPA>3.0 Stratos Idreos 17/49

18 employee (id:int, name:varchar(50), office:char(5), telephone:char(10), city:varchar(30), salary:int) data schema (1, name1, office1, tel1, city1, salary1) (2, name2, office2, tel2, city2, salary2) (3, name3, office3, tel3, city3, salary3) (4, name4, office4, tel4, city4, salary4) (5, name5, office5, tel5, city5, salary5) (6, name6, office6, tel6, city6, salary6) (7, name7, office7, tel7, city7, salary7) (8, name8, office8, tel8, city8, salary8) (9, name9, office9, NULL, city9, salary9) SQL:insert into employee (1, name1, office1, tel1, city1, salary1) cardinality=9 value does not exist Stratos Idreos 18/49

19 relational model+sql database professor (id,name, ) enrolled (studentid, courseid, ) course (id,name, profid, ) foreign key student (id,name, ) give me all students enrolled in cs165 select student.name from student, enrolled, course where course.name= cs165 and enrolled.courseid=course.id and student.id=enrolled.studentid join Stratos Idreos 19/49

20 enrolled (studentid,courseid, ) student (id,name, ) how do we join Stratos Idreos 20/49

21 normalization say schema about university db contains one table AllData(student ID,student name,student address, course name, grade, professor name, professor ID, professor telephone, ) good duplicates - tons of data - updates - but no joins Stratos Idreos 21/49

22 star schema dimension table 1 (id1, ) fact table (id1,id2, ) dimension table 2 (id2, ) Stratos Idreos 22/49

23 snowflake schema Stratos Idreos 23/49

24 Alex Liu, class /265 project adaptive denormalization 1st prize in ACM SIGMOD undergrad research competition Special Interest Group on Management of Data Stratos Idreos 24/49

25 NORMALIZED DATA DENORMALIZED DATA only fast scans but expensive to create, storage & updates good for updates, storage but we need joins Stratos Idreos 25/49

26 adaptive denormalization continuously physically reorganize data based on incoming query patterns (joins) denormalized fragments queries only need to fast scan normalized data possible denormalized space Stratos Idreos 26/49

27 constraints create table employee (id:integer, name:varchar(50) not null, must have a value office:char(5), at most 5 chars telephone:char(10), city:varchar(30), salary:integer, primary key (id) must be unique check (salary<100000)) must not become rich when and how do we enforce constraints Stratos Idreos 27/49

28 more SQL examples aggregations select max(gpa),avg(gpa),min(gpa) from students math select R.a - R.b + R.c from R nested select * from R where R.a IN (select b from S where C<10) set ops select * from R where a =10 UNION select * from B where b =20 Stratos Idreos 28/49

29 select avg(gpa), class, major from students where GPA>3.0 and class>1990 group by class, major order by class Stratos Idreos 29/49

30 base table Employee (id:int, name:varchar(50), office:char(5), telephone:char(10), city:varchar(30), salary:int) view to be used by managers in Berlin Employee-Berlin-Manager select * from employee where city= berlin how should we store views view to be used by all employees in Berlin Employee-Berlin-All select id,name,city,office from employee where city= berlin Stratos Idreos 30/49

31 why are models great? Stratos Idreos 31/49

32 other models? Stratos Idreos 32/49

33 it is summer now you know all about data systems you are building an augmented reality startup using Google Glass people wearing Google Glass can tag places/objects - voice/image recognition works fine tagging means assigning values, comments, etc to an object you can then query this data - again assume voice recognition works fine and a black box translates natural language to SQL how does the schema of your app look like? (tables, attributes, keys, relationships) (assume a limited working environment/features, say walking around Harvard square/yard) describe 2 interesting queries in SQL Stratos Idreos 33/49

34 a possible example q1: get all places where jenny said awesome q2: get all users that like what I like and are close by comment (id,user_id,oject_id,text, ) likes_comment (user_id,comment_id) object (id,name,location,telephone,date,url,color,taste, many more) user (id,name,location,device, ) likes_object (user_id,oject_id,) trust (user_id,user_id) select user.name, user.location select object.location from user, likes_object as L1, likes_object as from L2 object, user where L1.user_id=my_id and L1.object_id=L2.object_id where user.name and L2.user_id = jenny!=my_id and and user.id=l2.user_id and close(user.location,mylocation)=true comment.user_id=user.id and comment.text LIKE %awesome% Stratos Idreos 34/49

35 how do we store the object table? what if we want to add another kind of object? object (id,name,location,telephone,date,url,color,taste, many more) open research and business problem Stratos Idreos 35/49

36 design logical design physical design system design Stratos Idreos 36/49

37 declarative interface ask what you want so do db systems just work? db system Stratos Idreos 37/49

38 declarative interface ask what you want indexes/views/tuning knobs DBA but db cracking, adaptive* ideas db system Stratos Idreos 38/49

39 essential steps in using a database system experts/system admins clean schema load tune query user/apps Stratos Idreos 39/49

40 design logical design physical design system design next up: db architectures 101 Stratos Idreos 40/49

41 applications sql algorithms/operators database kernel design/implement numerous possible algorithms + data representations choose the best data source, algorithms and path for each query data data data Stratos Idreos 41/49

42 select min(a) from R where B<10 and C<80 algorithms/operators database kernel data data data parser optimizer execution storage Stratos Idreos 42/49

43 applications sql parser optimizer in/out admission execution storage database kernel Stratos Idreos 43/49

44 applications sql client programs thread 1 thread 2 thread 3 thread 4 thread 5 db program thread pool database kernel Stratos Idreos 44/49

45 applications sql parser in/out database kernel cpu optimizer thread pool memory execution transactions disk storage buffer pool is it good to have modules Stratos Idreos 45/49

46 Notes to remember models help create the right abstractions models help create >>1 applications over the same data we first need to clean, structure and load data data systems consist of software components Stratos Idreos 46/49

47 reading textbook: chapters 1, 3 (-3.5), 5 (-5.8,-5.9) intro + relational model + SQL browse the Fourth Paradigm Stratos Idreos 47/49

48 readings for next 3 classes Architecture of a Database System (Sections 1,2,3,4) by J. Hellerstein, M. Stonebraker and J. Hamilton The Design and Implementation of Modern Column-store Database Systems by D. Abadi, P. Boncz, S. Harizopoulos, S. Idreos, S. Madden Stratos Idreos 48/49

49 class 3 Models & Intro to DB Architectures DATA SYSTEMS prof. Stratos Idreos