RE: expdp and ORA-01555

From: Roberts, David (GSD - UK) <"Roberts,>
Date: Mon, 6 Apr 2009 15:36:26 +0100
Message-ID: <>

I think that this is unlikely to be the cause, but I'm sure I read somewhere (Possibly the book: Oracle Troubleshooting) that you can get Snapshot too old errors from read only tablespaces due to a feature of Oracle lazy writes, where either a table header or block header was not updated before the tablespace was placed in read only mode.  

The solution was to perform a full table scan on all the tables in the tablespace before placing the tablespace in read-only mode.  

Although I suspect that this is unrelated to your problem, as there seem to be LOB specific ORA-1555 problems which are more likely to be the cause, but thought I would mention it just in case.    


-----Original Message-----
[] On Behalf Of Rich Sent: 05 April 2009 16:35
Cc: Yong Huang; Oracle-L Freelists
Subject: Re: expdp and ORA-01555  

This is ORA-1555 on expdp, now on read only tablespace. Same table as before.

Solved this a while ago by moving the table to a separate tablespace and setting TS to read only before export, however, it is back.

We have also changed to:
Oracle 64-bit on RHEL 5.1 and different server (different reasons).

Tried to set event for 1555 error:
alter system set events '1555 trace name errorstack forever, level 12' however, there is no trace file in udump after the error.

The error is reported in the alert log and the datapump worker process trace (*dw01*) as well as the export log.

Don't have another server with which to test - this is production.

Checked for corruption per Note 787004.1 twice - no corrupt LOBs.

Also, have SR open with Oracle, again, but thought I would try to see if Yong (or any others) are [still] encountering this.

Any help?

On Wed, Aug 27, 2008 at 11:39 PM, Tanel Poder <> wrote:

Ah ok, I had missed the LOB corruption part in your post, thus neither retention nor pctversion settings help.

If corruption is involved, this might be happening:

  1. expdp scans through LOB blocks
  2. ...and hits a corruption error which means that the lob block reading function returns a failure code
  3. there's a bug in code which assumes that whenever this lob block reading function fails, it means the block was already overwritten (thus raises ORA-1555
Tanel Poder - n.ote this!

> -----Original Message-----
> From: Yong Huang []

> Sent: Thursday, August 28, 2008 02:27
> To: Tanel Poder;
> Cc: 'Oracle-L Freelists'
> Subject: RE: expdp and ORA-01555

> Thanks. I tried retention. Still the same error. I guess all
> these are for future space usage, not the already corrupted blocks.
> I'm guessing the cause of the error in is the same
> as in But Oracle partially fixed the problem so the
> PL/SQL block in Note:452341.1 doesn't detect it. I haven't
> tried to get an error stack. I won't be surprised if it looks
> like Richa's.
> Yong Huang
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Received on Mon Apr 06 2009 - 09:36:26 CDT

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