Database Management Systems
Test #2: Preparation
four or five questions.
I am aiming to make it shorter than midterm #1
so there is not as much time pressure.
The type of questions and layout of the test will be similar
the first test.
- E.g., What is the I/O cost of this query plan?
How many tuples is this query likely to return?
(Use assumptions of System R to estimate.)
- short answer
- E.g., Which join algorithm would be
most appropriate for this query?
- E.g., How would we need to modify the 2-pass sort-merge join
is not intended to be cumulative,
and so will not test directly on the subjects covered up to Midterm #1,
the physical database,
So not covered:
- physical database
- disk space manager
- buffer pool manager
- file, page, and record formats
- internals of index data structures
- B+ trees
- extendable and linear hashs
- basics of the external sort algorithm
everything we have done since Test I
builds on the material from before.
So in that sense,
you are responsible for the previous material
for this exam,
- indexes (needed for access paths) (Ch.8)
- prefix matching
- cost model for using
- clustered vs unclustered
- external sorting (Ch.13)
Many other relational algorithms are based on this,
and have the same performance issues.
- advanced issues
(e.g., double buffering, block reads and writes, etc.)
- query evaluation, overview (Ch.12)
- access paths
- cost model & System R
- reduction factors
- cost estimation
- query trees & alternative plans
- optimization "rules" like pushing selects
- evaluating the relational operators (Ch.14)
& access paths
- project with distinct
- nested loops join
- block nested loops join
- index nested loops join
- sort-merge join
- na´ve: sort first, then merge
- 2-pass: accomplishes join in two passes
- hash join (two pass)
- the set operations
- relational optimizer (Ch.12&15)
As covered in Chapter 12,
have gone through Chapter 15 very generally.
Nothing advanced from Chapter 15.
- System R
- left-join trees
- general about the join-enumeration algorithm
test will be closed-note, closed-book.
You may bring a calculator,
but the test will be designed so that any math
shouldn't need one.
There will be space on the text packet for writing answers.
I will bring extra paper, in case anyone needs it,
The test will be for the class lecture time,
so 75 minutes.