ORA-01555: Snapshot Too Old: Rollback Segment Number 6 With Name "_SYSSMU6_12

(Doc ID 1493515.1)

Last updated on MARCH 19, 2018

Applies to:

Oracle Database - Enterprise Edition - Version to [Release 11.1]
Information in this document applies to any platform.
***Checked for relevance on 01-Jul-2016***


  1. The following errors are reported in the application log or alert file:
    ORA-01555: snapshot too old: rollback segment number 6 with name "_SYSSMU6_12

    The error might occur only in the application log, but not necessarily in the alert file.
  2. There may or may not be a current SQL reported in the incident trace file:
    ----- Error Stack Dump -----
    ORA-01555: snapshot too old: rollback segment number with name "" too small
    ----- SQL Statement (None) -----
    Current SQL information unavailable - no cursor.

  3. Review of the tracefiles generated after setting the 1555 event reveals a call stack similar to:
    ... <- ktucloGetTxTableUndoRec <- ktucloGetMinPrepStartTime <- ktucloUsMinScn <- ktucloUsegScan <- ksb_run_managed_action <- ksbcti <- ksbabs <- kebm_mmon_main <- ksbrdp <- opirip <- ...


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