Oracle Point, Oracle Life.

Today, we experienced error EXP-00091 while we was exporting entire database.

EXP-00091: Exporting questionable statistics.
. . exporting table DEF$_AQCALL 0 rows exported

Cause:

The cause of this error is because the statistics may not be usable while Export was going to export statistics. Basically, the statistics are questionable because one or more of the following happened during export:

• A row error occurred
• Client character set or NCHARSET (where you run the Export) does not match with the server (database character set)
• A query clause was specified on export, only certain partitions or subpartitions were exported
• A fatal error occurred while processing a table

Possible Solutions:

After investigation, we got two methods to solve this problem. (It may not be problem becuase Oracle Metalink Note:376622.1 said it’s can be ignored.)

• keep the client character set to match the server (show parameter NLS)
• add one more export parameter option “STATISTICS=NONE”

When we do export, export utility prompts the following message:

“Export done in US7ASCII character set and UTF8 NCHAR character set server uses UTF8 character set (possible charset conversion”

The character set between client and server are mismatching. But, we don’t like to change character set readily. Our solution at this circumstance is to add parameter option “STATISTICS=NONE” because statistics is kindly unnecessary to keep for backup.

More:

Because we’re doing entire database export, the dump file is large over than 2G. If we do export with root user on Unix, that’s fine. The dump file can be extended as large as it should be. But, if we do it with normal oracle user on Unix, we’d better identify more dump files otherwise we’ll experience “ORA-24801 illegal parameter value in OCI lob function”. The upper limit of dump file size is 2G. If we don’t identify more dump files, exporting will raise this error.

In the future, if we need to import data to database, we need to include “STATISTICS=RECALCULATE” to recalculates statistics on import. (Oracle metalink Note:Note:159787.1)

More resource on “Using Differenct Releases and Versions of Export“.

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