Re: what's "enq:TX - contention

  • From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 29 Nov 2007 21:43:40 -0000

Several options, for example:

session 1 - execute some dml without commit

session 2 - alter tablespace X read only;

The tablespace cannot go read only until all current transactions commit - so session 2 picks the oldest
current transaction and waits on it using a TX mode 4.

The wait in 10g will show as "TX - contention"


Jonathan Lewis

Author: Cost Based Oracle: Fundamentals

The Co-operative Oracle Users' FAQ

----- Original Message ----- > Date: Thu, 29 Nov 2007 16:05:00 +0800
From: "Eagle Fan" <eagle.f@xxxxxxxxx>
Subject: Re: what's "enq:TX - contention"

any comments?

On Nov 27, 2007 12:19 AM, Eagle Fan <eagle.f@xxxxxxxxx> wrote:


In 10g, oracle has four TX wait events:

1. enq:TX - row lock contention
2. enq:TX - index contention
3. enq:TX - ITL
4. enq:TX - contention

I know the first three ones' meanings.

But what does the last one "enq:TX - contention" mean? I know it means
other TX enqueue types. But what's the *other* TX enqueues?

Could anybody give me some examples? We have insert sql causes this TX

I searched metalink and oracle-l, but most doc/threads are discussing the
first three ones.

Thanks a lot.


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