Database Refreshment Contest 9

[vjsreevs]

1)What are ACID properties ?
2)What are internal / external sorting/searching techniques ?
3)What are dense/sparse indexes ?
4)What is block anchoring ?
5)What is aggregation ?

[ajithcharles]

1)What are ACID properties ?

For any database to be certified as an RDBMS for a client/server environment
a database has to satisfyACID properties which mean
Atomicity
Consistency
isolation
Durability

[Mrs Chepeni]

3. Dense Index: An index record appears for every search key value in the file.In dense clustering index,the index record contains the search key value and a ptr to the first data record with that serach key value.All other records with the same search key value would be stored sequentially after the first record,since the index is clustering one, records are sorted on the same search key.
Sparse Index: An index record appears for only some of the search kay values. Index record contains a search key value and a pointer to the first data record with that serch key value.To locate a record, v find the index entry with the largest search key value that is less than or equal to search key value for which v r looking.v start at the record pointed by that index entry , and follow the pointers in the file until v find the desired record.