Morning Aman, >> Is it a correct thing to say that when the data buffer is >> being read from the disk, its first kept in the PGA and then >> later on, it would be copied from the PGA memory to the >> standard buffer cache? Not quite. >> If no, then its alright but if yes, why such behaviour is there? It isn't - unless of course Oracle changed things recently! <SNIP> >> If anyone can explain and >> clear this confusion, it would be just great! The disc buffer(s) are read from disc - assuming that they are not already in the buffer cache - and placed into the buffer cache directly. Your server process then returns the block or blocks you requested to your user process. Now, I have to say that the last time I dealt with this was way back at Oracle 8.0 (!!!) so I'm now looking forward to being (a) corrected and (b) educated by those who know better than me! Cheers, Norman. Information in this message may be confidential and may be legally privileged. If you have received this message by mistake, please notify the sender immediately, delete it and do not copy it to anyone else. We have checked this email and its attachments for viruses. But you should still check any attachment before opening it. We may have to make this message and any reply to it public if asked to under the Freedom of Information Act, Data Protection Act or for litigation. Email messages and attachments sent to or from any Environment Agency address may also be accessed by someone other than the sender or recipient, for business purposes. If we have sent you information and you wish to use it please read our terms and conditions which you can get by calling us on 08708 506 506. Find out more about the Environment Agency at www.environment-agency.gov.uk Information in this message may be confidential and may be legally privileged. If you have received this message by mistake, please notify the sender immediately, delete it and do not copy it to anyone else. We have checked this email and its attachments for viruses. But you should still check any attachment before opening it. We may have to make this message and any reply to it public if asked to under the Freedom of Information Act, Data Protection Act or for litigation. Email messages and attachments sent to or from any Environment Agency address may also be accessed by someone other than the sender or recipient, for business purposes. If we have sent you information and you wish to use it please read our terms and conditions which you can get by calling us on 08708 506 506. Find out more about the Environment Agency at www.environment-agency.gov.uk -- //www.freelists.org/webpage/oracle-l