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ORA-01555 "Snapshot too old" - Detailed Explanation (Doc ID 40689.1)

Last updated on OCTOBER 10, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 9.2.0.8 to 11.2.0.3 [Release 9.2 to 11.2]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.
***Checked for relevance on 25-Apr-2012***

Purpose

This article will discuss the circumstances under which a query can return the Oracle error ORA-01555: snapshot too old: rollback segment number string with name "string" too small. The article will then discuss actions that can be taken to avoid the error and finally will provide some simple PL/SQL scripts that illustrate the issues discussed.

Scope

It is assumed that the reader is familiar with standard Oracle terminology such as 'rollback segment' and 'SCN'. If not, the reader should first read the Oracle Database Concepts manual and related Oracle Database documentation.

Details

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In this Document
Purpose
Scope
Details
 Terminology
 ORA-01555 Explanation
 Solutions
 Examples
 Special Cases
 Summary
References

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