Actual execution process of Oracle delete

Today, we will mainly introduce the actual execution process of Oracle delete. First, we will explain the detailed operation procedures of Oracle Delete and Commit. The following describes the specific content, I hope this will help you in your future studies.

1) Delete) Process

Oracle read Block (data Block) to Buffer Cache Buffer (if the Block does not exist in Buffer );

Record the details of Oracle Delete operations in Redo Log Buffer;

Create an Undo rollback entry in the transaction table of the corresponding rollback segment header;

Store the image before the record is created in the Undo Block rollback Block;

Delete records on the corresponding data blocks in the Buffer Cache, and mark the corresponding data blocks as Dirty ).

2) Commit Process

Oracle generates an SCN;

Mark the transaction status as Commited in the rollback segment transaction table;

LGWR Log read/write process) Flush Log Buffer to Log files;

If the data Block is still in the Buffer Cache, the SCN will be recorded on the Block Header, which is called fast commit;

If the Dirty Block has been written back to the disk, the next process accessing the Block will obtain the state of the transaction from the rollback segment and confirm that the transaction is committed. Then the process obtains the committed SCN and writes it back to the Block Header, which is called the delay Block clearing.

The above content describes the process analysis of Oracle Delete and Commit operations, hoping to help you in this regard.