what exactly does 'cosistent read' mean?

Hi ,

In gv$bh view , there exists a status flag which describes the buffer's status. One of these status is 'cr' , consistent read. And gv$sess_io view has a column called 'consistent_gets'.

My question about this 'consistent_gets' . What i know is consistent_get is used for multi-versioning . My system is a datawarehouse and i have no updates during a day , but i see lots of consistent gets in v$sess_io , may be my understanding about cr is wrong. Also , for gv$bh :

In a session i create a simple table then insert a record then commit , close this session.

In one new session , i update this record , in another session i select this record. Now when i look at the gv$bh view i see 'cr' version of the block , but when i run the second sessions multiple times , for each execution , a new 'cr' block is created in gv$bh. But i expect to see only one .

I will be appreciated if someone helps.

Kind Regards,
hope Received on Mon Jun 14 2004 - 03:07:16 CDT