Oracle Database / SQL Performance & Memory
Find current Oracle temporary-space consumers
A sort-heavy request or temporary LOB can consume TEMP while several users report failures. Identify current allocations and the sessions involved.
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 s.sid, s.serial#, u.tablespace, u.segtype, u.blocks FROM v$tempseg_usage u JOIN v$session s ON u.session_addr = s.saddr ORDER BY u.blocks DESC;Read the result
BLOCKS are allocated temporary blocks and require the correct block size for byte conversion. Allocations may change before the next sample.
Resolve and verify
Map the largest consumer to its SQL and business operation. Tune excessive work or plan capacity based on concurrent demand, then verify temporary usage recedes.
Operational precautions
Do not delete tempfiles or kill all large consumers without understanding in-flight work.