(Strongly prefer plain text. Will accept PDF or MSWord documents, if typed.)
Handwritten answers, on paper or as photographs, strongly discouraged.
This is an individual assignment. All work must be entirely your own. You should not look at any other student's work (in whole or in part, on paper or on screen), nor allow anyone else to look at yours, nor discuss the assignment with other students, during the course of this assignment. Nor may you submit the work of software programs as your own.
Put your own name at the top of your own homework answers.Note: T<number> identifies a transaction numbered number. R(<letter>) identifies a read operation on database object letter. W(<letter>) identifies a write operation on database object letter.
Questions
- Consider the following schedule:
T1: R(D), T1: W(A), T1: R(D), T3: R(B), T2: R(D), T2: R(A), T3: R(A), T1: R(C), T2: W(A),
T2: R(B), T1: W(C), T2: W(B), T3: R(C), T3: R(D)
Is the schedule serializable? If so, show an equivalent serial transaction
order. If not, precisely describe why not.
If relevant, fill in this table with the equivalent serial transaction
order. Time proceeds from left to right, with only one action possible in each
time slot.
Schedule Time 1 Time 2 Time 3 Time 4 Time 5 Time 6 Time 7 Time 8 Time 9 Time 10 Time 11 Time 12 Time 13 Time 14 Time 15 T1 T2 T3 - Consider the following schedule:
T2: R(A), T1: R(B), T3: W(B), T2: R(C), T1: W(D), T2: W(C), T1: R(B), T1: W(B), T2: R(D), T2: W(D), T2: W(A), T3: R(D), T3: W(D)
Is the schedule serializable? If so, show an equivalent serial transaction order. If not, precisely describe why not.
If relevant, fill in this table with the equivalent serial transaction order. Time proceeds from left to right, with only one action possible in each time slot.
Schedule Time 1 Time 2 Time 3 Time 4 Time 5 Time 6 Time 7 Time 8 Time 9 Time 10 Time 11 Time 12 Time 13 Time 14 Time 15 T1 T2 T3 - During Analysis:
- a) What log records are read?
- b) What are the contents of the Dirty Page Table (DPT) and the transaction table at the end of the analysis stage?
- During Redo:
- a) What log records are read?
- b) What data pages are read?
- c) What operations are redone? (Assume no updates made it out to stable storage, like a hard disk, before the crash, except updates written to stable storage as part of a transaction commit.)
- During Undo:
- a) What log records are read?
- b) What operations are undone?
- Consider these tables (from Homework 2).
Astronaut(astroID: integer, lastname: string, firstname: string, birthdate: date, deathdate: date, country: string)
ExperienceWith(astroID: integer, officialair: string, experiencetype: string, yearstart: integer);
Airplane(officialair: string, nickname: string, manufacturer: string, firstflight: date, numberBuilt: integer, planetype: string);
Assume the Astronaut table has 500 tuples in it, the ExperienceWith table has 10,000 tuples in it, and the Airplane table has 5,000 tuples in it.
Also consider this question:
Find the official names of airplanes and the number built, where an astronaut has experience on that airplane as an "instructor pilot", and that astronaut flew for the country of Italy.
One possible solution to the question is:
SELECT officialair, numberBuilt
FROM Airplane Air, ExperienceWith EW, Astronaut Ast
WHERE Air.officialair = EW.officialair AND EW.astroID = Ast.astroID AND EW.experiencetype = "instructor pilot" AND Ast.country = "Italy"
a) Translate this SQL query into a corresponding relational algebra expression (and write down the expression).
b) Then draw a System-R style query plan for your relational algebra expression.
c) Using equivalencies of relational algebra expressions, re-write your relational algebra expression into a more efficient form, if possible. Draw the new, corresponding query tree. Explain why your new expression is more efficient.
For questions 3-5, consider the execution of the ARIES recovery algorithm given the following log:
| LSN | Log Record |
| 00 | begin_checkpoint |
| 05 | end_checkpoint |
| 10 | Update: T1 writes P3 |
| 20 | Update: T3 writes P2 |
| 30 | Update: T2 writes P1 |
| 40 | Update: T1 writes P4 |
| 50 | Update: T4 writes P2 |
| 60 | T1 commit |
| 70 | Update: T3 writes P1 |
| 80 | T3 abort |
| 90 | CLR: Undo T3 LSN 70 |
| 100 | Update: T2 writes P4 |
| 110 | T4 abort |
| 120 | T1 end |
| 130 | CLR: Undo T3 LSN 20 |
| X - crash, restart |
For the questions below, when you are asked which log records are read, you are to supply the exact list of LSNs from log above. When data pages are asked for, you are to supply the exact list of page identifiers from the log above. And so on. Be specific and concrete in your answers, answering specifically for the provided log.
Operations can be identified using the LSN for the log record recording that operation. (So, of course, can the log record itself.)
Generic statements or quotations from the textbook (or slides) will earn 0 points. Example: "all the pages" == 0 points. "P1, P2 and P3" == more than 0 points, assuming those are the pages read. (Don't use English. List the log record numbers, list the page numbers, etc.)
For questions 3-5, parts a-c are separate questions. Answer a through c separately. Label your answers so that it is clear what is your answer to '3.a' and what is your answer to '4.c', and so on.