Oracle temp I/O wait pressure alert


The Temp I/O Wait Pressure alert notifies you when its configured condition is met on Oracle instances so you can investigate and respond.

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Alert summary

  • Platform: Oracle
  • Alert category: Query
  • Default enabled: true
  • Default evaluation frequency: Minute
  • Threshold label: % of DB time
  • Unit: % of DB time

What Mini DBA checks

Mini DBA describes this alert as: Oracle temporary I/O waits as a percentage of current database time Sustained temp I/O pressure usually indicates sorts, hash joins, reporting queries, index operations, or other work spilling to temporary tablespace Mini DBA evaluates this alert once a minute so changes are detected quickly. Because duration is used, Mini DBA can avoid treating a single short spike as a full incident when the condition clears quickly.

How this alert helps

This alert shows Oracle temporary I/O waits consuming a significant share of database time. Sustained pressure usually means sorts, hash joins, reporting queries, index operations, or other work is spilling to temporary tablespace.

When to enable it

Enable it once the instance has a normal workload baseline. It is especially useful on busy OLTP, reporting, and integration systems where resource pressure can quickly become user-visible.

Threshold guidance

Threshold meaning: % of DB time. Major threshold: 20 % of DB time. Minor threshold: 10 % of DB time. Comparison direction: over. Duration is used, so prefer requiring the condition to persist before paging people for transient spikes. For an over-threshold alert, decreasing a threshold makes that severity fire sooner; increasing it tolerates more load or pressure. Set the minor threshold as an early-warning level and the major threshold at the highest acceptable value for the service.

Remediation for an active alert

Identify the SQL and operations using temporary space, review their plans and workarea execution, and compare PGA settings and memory headroom. Tune the workload or workarea sizing carefully; add temporary storage capacity when genuine demand requires it.

Investigation workflow

  1. Record the Temp I/O percentage, dominant wait events, SQL statements, and temporary-tablespace use.
  2. Review plans and workarea statistics for sorts, hashes, spills, and inaccurate estimates.
  3. Compare PGA configuration and total concurrency with host memory headroom before changing settings.
  4. Confirm that temporary I/O waits and query latency return to baseline.

Avoiding alert noise

If this alert is noisy, check whether the workload naturally has short bursts. Raise the duration or threshold for expected batch windows, but keep a lower route for production systems where user-facing latency matters. Avoid simply disabling the alert until you know whether the noise is caused by threshold choice or by a real capacity trend.

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