Oracle Database / Storage, Undo & Redo
ORA-30036: investigate undo tablespace exhaustion
A write-heavy transaction may fail when undo cannot extend. Active transactions, retention settings and storage limits all affect available undo.
Environment and inputs: Oracle Database 19c baseline · SQL*Plus-compatible SQL unless RMAN, DGMGRL, ADRCI or a host shell is specified. Check release, patch level, edition and container first.
Start with this diagnostic
Use the stated SQL, RMAN, DGMGRL or host shell and replace sample names with approved targets. DBA and V$ views need authorized catalog access in the correct container. Do not grant broad privileges for an example.
SELECT tablespace_name, status, SUM(bytes) AS bytes FROM dba_undo_extents GROUP BY tablespace_name, status;Read the result
ACTIVE, UNEXPIRED and EXPIRED extents describe different reuse states. The totals are a snapshot, not a forecast of the largest pending transaction.
Resolve and verify
Compare transaction growth, undo capacity, autoextend limits and retention guarantee. Plan safe capacity or workload changes and verify the business transaction's recovery state.
Operational precautions
Do not delete undo datafiles or force transaction termination without a rollback and application recovery plan.