Friday, June 23, 2006

Berkeley DB: Part one

Berkely DB concepts

1.DB databases contains records
2. A record contains a key and value.
3. key/data of a record , the data cen be complex.
4. DB database similar like a table in a relation
5. DB applications could use more than one DB databases ( more than 1 tables)
6. The DB database containing records have an assoicated access methods to them
a) Btree
b) Hash
c) Queue
7. Typical DB applications will using many DB databases.
8. Retrieving the records = get()
Putting the records = put()
9. If the databases does not support duplicate records , the next time you insert the data records with existing key, this key replaces the old key.

10. In addition to handles, cursors could be used to insert/retrieve data. Cursors could be used to seek to the data
11. DB provides secondary database which serves as an index to the primary database. Cursors are iterators over the records on the database.
12. Btree access method the most popular method to retrieve data.
13. RecNo , logical records numbers as keys.

Arbitrary Data (strings) Btree or Hash
logical records number (integer) Queue or Recno.

14. Small working datasets no difference between RecNo.

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