Oracle Database Error Solutions & DBA Guide

📅 Last Updated: August 2026 This guide explains the Oracle Data Pump/Classic Export warning EXP-00091: Exporting questionable statistics , its common causes, how to diagnose it, and why the warning should not automatically be treated as a failed export. EXP-00091: Exporting Questionable Statistics – Causes, Diagnosis and Solutions in Oracle Database EXP-00091: Exporting questionable statistics is a warning that can appear while performing an Oracle Classic Export using the legacy exp utility. The message can be confusing because the export may continue and complete successfully even though Oracle reports questionable optimizer statistics. This is particularly important when working with older Oracle Database environments where the traditional exp and imp utilities are still used for migration, backup, or data-transfer activities. Important: EXP-00091 does not automatically mean that the exported table data is corrupt or that the entire export has...

Unable to Connect to Oracle Database from Windows SQL*Plus Client – Character Set and Oracle Net Troubleshooting 📅 Last Updated: August 2026 This guide explains how to troubleshoot a situation where a Windows SQL*Plus client is unable to establish a reliable connection to an Oracle Database hosted on a Linux server. The article focuses on character-set compatibility, Oracle Net connectivity, NLS configuration, and safe diagnostic procedures. Oracle Database connectivity problems can sometimes be misleading. A connection that hangs, closes unexpectedly, or fails only from a particular client may initially appear to be a network problem. However, the actual cause can be located at several different layers, including Oracle Net, the Oracle client installation, environment variables, NLS configuration, database character-set compatibility, or application-specific settings. This article is based on a real-world Oracle E-Business Suite environment in which a database hos...