ORA-01555 "Snapshot too old" - Detailed Explanation
(Doc ID 40689.1)
Last updated on JANUARY 30, 2022
Oracle Database - Enterprise Edition - Version 22.214.171.124 to 126.96.36.199 [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.
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.
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.
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