Skip to Main Content

Breadcrumb

May 4th

Question and Answer

Connor McDonald

Thanks for the question, richard.

Asked: January 11, 2005 - 8:56 pm UTC

Last updated: February 25, 2021 - 5:34 am UTC

Version: 9.2.0.4

Viewed 10K+ times! This question is

You Asked

Hi tom,

Thanks a lot for taking time to answer questions.

In Oracle database 9.2.0.4 for windows 32-bit.

I could run exp without any problems. But when I run export with query="where ..." I got a lot of:

"exp-00091 exporting questionable statistics"

The question is: why this happens? and how to fix it?

Thanks a lot.

and Tom said...

</code> http://docs.oracle.com/cd/B10501_01/server.920/a96652/ch01.htm#1005905

there is nothing "to fix", it is working as expected -- the query clause will have that message generated (because the stats it is pulling are "questionable", you might have to analyze on the import since you are getting SOME not all of the rows)

see
http://docs.oracle.com/cd/B10501_01/server.920/a96652/ch02.htm#1005605 <code>

on the import, you can use "statistics=safe" if you want to skip questionable statistics from being imported.

It is just a message telling you "there are questionable stats", caveat emptor.

Rating

  (8 ratings)

Is this answer out of date? If it is, please let us know via a Comment

Comments

Dave, January 12, 2005 - 11:04 am UTC

I havent read those docs to be honest, but you can get it when your NLS_LANG environment variable is wrong as well.

Usually just ignore it and redo the stats after an import

Tom Kyte
January 12, 2005 - 11:09 am UTC

the first link above states when:

<quote>
The precalculated optimizer statistics are flagged as questionable at export time if:

* There are row errors while exporting
* The client character set or NCHAR character set does not match the server character set or NCHAR character set
* A QUERY clause is specified
* Only certain partitions or subpartitions are exported

</quote>




I am still getting this warning

Vikas Khanna, January 05, 2006 - 5:33 am UTC

I am exporting a particular schema objects using OWNER option with ROWS = N, then

also it gives me the warning 'Exporting questionable stats.

1. I am not exporting using Where Clause
2. I am exporting from the db machine itself
3. I am exporting the complete tables and not partitions.

Still I get these warnings.

Thanks

Tom Kyte
January 05, 2006 - 10:44 am UTC

It is exporting statistics and tell you "they are questionable" - is that causing something to not work?


00091, 00000, "Exporting questionable statistics."
// *Cause: Export was able export statistics, but the statistics may not be
// usuable. The statistics are questionable because one or more of
// the following happened during export: a row error occurred, client
// character set or NCHARSET does not match with the server, a query
// clause was specified on export, only certain partitions or
// subpartitions were exported, or a fatal error occurred while
// processing a table.
// *Action: To export non-questionable statistics, change the client character
// set or NCHARSET to match the server, export with no query clause,
// export complete tables. If desired, import parameters can be
// supplied so that only non-questionable statistics will be imported,
// and all questionable statistics will be recalculated.


Sounds like a character set mismatch then.

[tkyte@dellpe ~]$ exp userid=/ tables=t rows=n
Export: Release 10.2.0.1.0 - Production on Thu Jan 5 10:37:46 2006
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Export done in US7ASCII character set and AL16UTF16 NCHAR character set
server uses WE8ISO8859P1 character set (possible charset conversion)

Note: table data (rows) will not be exported

About to export specified tables via Conventional Path ...
. . exporting table T
EXP-00091: Exporting questionable statistics.

Export terminated successfully with warnings.

[tkyte@dellpe ~]$ export NLS_LANG=.WE8ISO8859P1

[tkyte@dellpe ~]$ exp userid=/ tables=t rows=n

Export: Release 10.2.0.1.0 - Production on Thu Jan 5 10:38:04 2006

Copyright (c) 1982, 2005, Oracle. All rights reserved.


Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Export done in WE8ISO8859P1 character set and AL16UTF16 NCHAR character set

Note: table data (rows) will not be exported

About to export specified tables via Conventional Path ...
. . exporting table T
Export terminated successfully without warnings.
[tkyte@dellpe ~]$


MLA's Review on EXP-00091

Marinko Laban, March 03, 2006 - 11:14 am UTC

Especially one of the other comments (refering to NLS_LANG differences) was useful, as this was the cause at my system.
I installed Oracle with AL32UTF8 lang, but somehow my NLS_LANG registry value in Home0 was still WE8MSWIN1252.

Correcting the NLS_LANG in the registry solved it.

Setting NLS_LANG

Suresh, January 05, 2007 - 2:50 pm UTC

Why was the dot(.) used before the char set in your earlier export setting? I tried without the dot and the questionable stats still persisted and when prefixing the dot solved the issue.

export NLS_LANG=.WE8ISO8859P1
Tom Kyte
January 06, 2007 - 8:42 am UTC

because NLS_LANG is language.characterset

if you remove the dot, you haven't set the characterset.

import in different tablespaces

ajeet, January 11, 2007 - 9:32 am UTC

Hi Tom,
I have 40 tablespaces in one of my old 9i database.I want to export it and then import in 10g database.while importing in 10g - i want to use fewer tablespaces..and change the name of tablespaces too - is it possible using import. I know that it is possible using data pump.but is it possible in 9i..using export/import.

Export by security

Sawsan, June 18, 2008 - 5:07 am UTC

Hi Tom,

If i have dump file from other schema i can easily create newuser and write imp newuser/password file=c:\dump.dmp full=y
I ask about a sucirty or a way to prevent import the dmp file until it has authority in any how ?

thanks alot
Tom Kyte
June 18, 2008 - 1:32 pm UTC

what does "until it has authority in any how" mean exactly?

Not sure what you are trying to do here.

export NLS_LANG=.WE8ISO8859P1

A reader, October 11, 2012 - 1:11 am UTC

tom,
thanks i got my issue solved with this parameter "<export NLS_LANG=.WE8ISO8859P1 >"
lots of applause to mr.richard for demand this question.

but i'm not getting the hang of ".WE8ISO8859P1" parameter
what fact (.) is representing here in "--->.WE8ISO8859P1"


Tom Kyte
October 11, 2012 - 8:08 am UTC

the format of the NLS_LANG parameter is "language.characterset"


you are giving just the characterset part so you have to lead with a dot to tell us this is a characterset not a language.


http://docs.oracle.com/cd/E11882_01/server.112/e16604/ch_eleven.htm#sthref1050

COMO EXTRAIR DADOS DO ORACLE: 12.2.7

bruno perez, February 24, 2021 - 11:58 am UTC

Alguém poderia me ajudar a criar uma conexão com o banco de dados ORACLE?

Gostaria de criar uma conexão que se atualizasse automaticamente.

Pelo que andei pesquisando é possível conectar via Microsoft ACCESS.

Mas não sei como fazer isso, e não temos muita informação sobre isso na internet.

CREATE TABLE INSERT
Connor McDonald
February 25, 2021 - 5:34 am UTC

Se você está apenas começando com o Oracle, posso sugerir que um bom lugar para começar seria livesql.oracle.com, que permite digitar comandos SQL como forma de aprendizado.

Além disso, verifique apex.oracle.com para começar a criar aplicativos, bem como usar SQL