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Support Article

Poor performance causing ORA-01555 snapshot too old errors



Users encounter errors when attempting to submit updates to their work items. Administrators are observing ORA-01555 errors in the PegaRULES logfile at these times.

Error Messages

java.sql.SQLException: ORA-01555: snapshot too old: rollback segment number with name "" too small
ORA-22924: snapshot too old

at oracle.jdbc.driver.T4CTTIoer.processError(
at oracle.jdbc.driver.T4CTTIoer.processError(
at oracle.jdbc.driver.T4CTTIoer.processError(
at oracle.jdbc.driver.T4C8TTILob.processError(
at oracle.jdbc.driver.T4CTTIfun.receive(

Steps to Reproduce

This error intermittently occurs while submitting or updating the data from the application.

Root Cause

Indexes were missing from several custom tables.  This caused the tables to perform very poorly, which stresses the undo segments.  This caused the undo retention segments to fill up and ORA-01555 errors to occur.


Ensure that your custom tables have indexes built on the columns which are commonly used for selection or update criteria.

Published February 26, 2016 - Updated October 8, 2020

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