关于oracle的update

Alex螺丝钉

Yong Huang 发表于 2015-7-8 22:25
> 这段英文可以在哪个文档上找到呢？

You mean the English sentence in msg #4? Nowhere. I wrote it.
...

I mean, Will a transaction hold the block in current mode during the whole transaction or just the moment it performs the dml?

Yong Huang

A session will hold the block in current mode during its change to the block, and continues to hold it until another session requests for the block in current mode (if it's not blocked by a conflicting TX lock, e.g. when it wants to update the *same* row).

> 哥，你收我做徒弟吧

Sorry. I don't know how to do that! But thanks for your compliment.

Alex螺丝钉

Yong Huang 发表于 2015-7-9 22:48
A session will hold the block in current mode during its change to the block, and continues to hold  ...

Thanks!
Sorry to bother you again. I came across a paragraph * A connection may have zero, one, or more sessions established on it. Each session is separate and independent, even though they  all share the same physical connection to the database. A commit in one session does not affect any other session on that connection. In fact, each session using that connection could use different  user identities! *  while I was reading Expert_Oracle_Database_Architecture, one of Thomas Kyte's books.
I am not sure about what he really means by the last senetence* each session using that connection could use different  user identities!*.  Here are two of my questions.
1. Could two users share one connection?
2.When will Oracle establish a new connection?

Yong Huang

> Could two users share one connection?

I found the pages in Tom Kyte's book and read the section. He didn't show examples of different users simultaneously using one single connection. But if your database runs in shared server mode, one shared server or dispatcher process can be used by different sessions (from the same *or* different user accounts) at different times, not simultaneously. I'm not sure how to make different sessions run on one single connection *not* at different times. Some tools may allow us to do that. Sqlplus cannot.

Database Resident Connection Pooling (DRCP) is something I don't have knowledge of. It may allow us to do that too. The step-by-step procedure is in
Master Note: Overview of Database Resident Connection Pooling (DRCP) (Doc ID 1501987.1)
Maybe you can try and let us know.

> When will Oracle establish a new connection?

That's the default behavior. I mean, sqlplus username/password@connectidentifier establishes a new connection.

Alex螺丝钉

Yong Huang 发表于 2015-7-11 03:43
> Could two users share one connection?

I found the pages in Tom Kyte's book and read the section ...

Thank you so much