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 Consider the instance of the Students relation shown in Figure 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.

Solution

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

Consider the instance of the Students relation shown in Figure 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 to identify a tuple.

Is that correct?

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, ); Grant (66, 22, 40000).