Topic: Backup & Recovery >> PCTFREE,PCTUSED AND FREELIST
|
Disclaimer: The purpose of all dbapool forums including OCP and Other Oracle Certification forums is to help each other with specific issues but not to share dump and copyrighted exam content, materials or intellectual property.
You may review the entire Oracle Certification Program Candidate Agreement online Here.
|
|
|
|
| Title: PCTFREE,PCTUSED AND FREELIST |
| seema |
Posted: Sep 19, 2008 12:51:42 AM |
Total Post: 70
Joined: Jan, 2008
|
| can you please tell me about pctfree,pctused and freelist with good example???? |
|
|
 balaji |
| Posted: Sep 19, 2008 04:48:43 AM |  |
|
Total Post: 162
Joined: May, 2008
|
Hi,
pctfree and PCTUSED are the block storage parameters.
1. pctfree- This parameter is used to specify how much space should be left in the block for updates.
For eg. if The pctfree for a block is 30, then Oracle keeps on adding new rows to the block until the block is 70 % full. It leaves the 30 % for future updates. That is, in case, any row is updated and requires some more space, it is taken out from the 30 % remaining in the Block. U should specify the Value of this parameter HIGH if future updates in the rows of the table are going to need more space. In case ur table is less prone to updates, then this value can be specified LOW.
PCTUSED : As I have mentioned above, Oracle stops INSERTING new Rows in a table when the space usage reaches the pctfree limit.
Now consider this ---- When should Oracle start inserting new rows in the Block ?
PctUSED parameter is taken into consideration for the answer of the above question.
Suppose u have specified PCTUSED as 40 %. and pctfree as 20 %.
1. Oracle will keep on inserting new rows till the space is 80 % used. It will reserve the remaining 20% for future updates.
2. To start adding new rows again to the block, Oracle will check the space in the Block and the PCTUSED parameter.
3. When the space falls below 40 %, Oracle will start adding new rows to the block.
for freelist ,check this link
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:950845531436
Regards,
Balaji
|
|
|
|
|
| Time Zone: EDT |
Send this thread to your friend |
|
|
|
|
Forum Rules & Description
Who Can Read The Forum? Any registered user or guest
Who Can Post New Topics? Any registered user
Who Can Post Replies? Any registered user
|
| |
Get FREE Magazines
|
Top 10 Forum User
|
| Murtuja Khokhar | 857 |
| Mohammed Taj | 746 |
| positive fanatic | 483 |
| Jayanta Sur | 479 |
| Vigyan Kaushik | 386 |
| Vinoth Kumar | 357 |
| Gopu Gopi | 340 |
| Gitesh Trivedi | 322 |
| neeraj sharma | 258 |
| Ramesh Jois | 246 |
|
|
