1. what is the Major difference Between Export Backup and Expdp backup.?
Ans:- 1. export we use in the 9i oracle new features come expdp into 10g which is also called the data pump backup.
2. Both of are logical backup means ;- Boths are creating whole database command into online mode when you will check the both backup you will find like create database abc;create table abc;insert into abc etc.............;
3. we can schedule export backup from client machine we can start expdp backup from client machine and backup will create on Db Server.
4. we can 'pause' the expdp backup but we cant pause the export backup.
5.Multiple server parallel process work for expdp backup but in case of export single process work.
6.Data Pump will recreate the user, whereas the old imp utility required the DBA to create the user ID before importing.
7.Data Pump does not use the BUFFERS parameter.
2. what is the difference between row migration and row chaining?
Ans:-
When rows are inserted into a block, the database engine reserves some free space for future updates. You define the amount of free space reserved for updates by using the PCTFREE parameter. For ex. I inserted six rows in the block. Since the limit set through PCTFREE has been reached, this block is no longer available for inserts.When a row is updated and its size increases, the database engine tries to find enough free space in the block where it’s stored. When not enough free space is available, the row is split into two pieces. The first piece (containing only control information, such as a rowid pointing to the second piece) remains in the original block.This kind of row is called a migrated row
Row chaining:- When a row is too big to fit into a single block, it’s split into two or more pieces. Then, each piece is stored in a different block, and a chain between the pieces is built. This type of row is called achained row