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Tutorial 19. Dina Said. Indexing Data. 1. A data entry k* is an actual data record (with search key value k 2. A data entry is a (k, rid) pair, where rid is the record id of a data record with search key value k .

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Tutorial 19

Dina Said

Indexing Data

1. A data entry k* is an actual data record (with search key value k

2. A data entry is a (k, rid) pair, where rid is the record id of a data record with search key value k.

3. A data entry is a (k, rid-list) pair, where rid-list is a list of record ids of data records with search key value k.

Indexing Data

1. A data entry k* is an actual data record (with search key value k  Primary Index

2. A data entry is a (k, rid) pair, where rid is the record id of a data record with search key value k. Secondary Index

3. A data entry is a (k, rid-list) pair, where rid-list is a list of record ids of data records with search key value k.

Duplicates
• Two data entries are said to be duplicates if they have the same value for the search key field associated with the index.
Indexing Data

1. A data entry k* is an actual data record (with search key value k  Can’t have duplicates

2. A data entry is a (k, rid) pair, where rid is the record id of a data record with search key value k. May have duplicates

3. A data entry is a (k, rid-list) pair, where rid-list is a list of record ids of data records with search key value k.

Duplicates
• If no duplicates exist
• The search key contains some candidate key
• We call the index a unique index.
Problem 10.10

Consider the instance of the Students relation shown in Figure 10.22.

Show a B+ tree of order 2 in each of these cases below, assuming that duplicates are

handled using overflow pages. Clearly indicate what the data entries are (i.e., do not use the k∗ convention).

1. A B+ tree index on age using Alternative (1) for data entries.

Problem 10.10

Consider the instance of the Students relation shown in Figure 10.22.

Show a B+ tree of order 2 in each of these cases below, assuming that duplicates are

handled using overflow pages. Clearly indicate what the data entries are (i.e., do not use the k∗ convention).

2. A dense B+ tree index on gpa using Alternative (2) for data entries. For this

question, assume that these tuples are stored in a sorted file in the order shown

in Figure 10.22: The first tuple is in page 1, slot 1; the second tuple is in page

1, slot 2; and so on. Each page can store up to three data records. You can use

page-id, slot to identify a tuple.

Show a B+ tree of order 2 in each of these cases below, assuming that duplicates are

handled using overflow pages. Clearly indicate what the data entries are (i.e., do not use the k∗ convention).

2. A dense B+ tree index on gpa using Alternative (2) for data entries. For this

question, assume that these tuples are stored in a sorted file in the order shown

in Figure 10.22: The first tuple is in page 1, slot 1; the second tuple is in page

1, slot 2; and so on. Each page can store up to three data records. You can use

<page-id, slot> to identify a tuple.

3-d tree
• Construct a 3-d tree using the following dimensions: age (int), years with the company (int), salary (real) for the following database: John(60, 24, 64,000); Scott(25, 2, 50,000); Charlie(38, 18, 54000); David(55, 29, 68,400); Ellen(27, 7, 55000); Frank(57, 17, 115000); Grant (66, 22, 40000).