SQL
Oracle diagnostics, autonomous.
dbexpertAI runs Oracle detection paths every 90 seconds — wait-event analysis, plan stability, undo/redo pressure, RAC interconnect health, and PGA/SGA sizing — and delivers root cause with the AWR-grade evidence behind it.
Oracle gives you the richest diagnostic surface of any database — v$ views, ASH, AWR — and buries the signal in it. The investigation discipline exists (every senior Oracle DBA reads wait events the same way); what's usually missing is someone running it continuously instead of after the incident. That's precisely the encodable part.
Failure modes we detect
How Oracle actually fails in production
Plan instability after statistics or bind-peeking changes
A new histogram, a bind-variable peek at an unrepresentative value, or an adaptive-plan flip sends a critical query onto a bad plan. Business impact is instant; the evidence trail (v$sql plan versions, ASH samples) is complete but nobody is reading it in real time.
ORA-01555 and undo pressure
Long-running queries die with snapshot-too-old while batch jobs churn undo. The fix is never "increase undo and pray" — it is knowing which sessions consume undo, whether retention matches query duration, and which commit patterns are the real problem.
RAC: global cache waits and interconnect trouble
gc buffer busy and gc cr block lost waits mean blocks ping-ponging between instances or a struggling interconnect. Applications experience random slowness; the diagnosis requires correlating cluster wait events across instances — mechanical, if encoded.
Log-file-sync stalls
Commit latency spikes trace to LGWR: undersized redo, slow storage under the logs, or commit-storm application behavior. Distinguishing the three takes a specific evidence sequence — each has a different fix and a different owner.
PGA/SGA pressure and temp spills
Workarea shortfalls send sorts and hash joins to TEMP, multiplying I/O. Memory advisors hold the answer; detection paths read them continuously and flag when automatic memory management has drifted against the workload.
A real diagnosis, walked through
What a Oracle detection path delivers
// symptom
Nightly settlement batch that finishes by 02:00 is still running at 06:30. No code changes.
// diagnostic evidence
- ASH: the batch session spent 92% of the night on db file sequential read against one statement
- v$sql: that statement's plan hash changed at 22:14 — nested-loops now driving a 40M-row probe
- 22:10 auto-stats job gathered fresh statistics on the settlement table; new histogram on a skewed column
- bind peeking at an unrepresentative value locked in the wrong join method
// root cause
The 22:10 statistics run plus bind peeking flipped the settlement query to a nested-loops plan that does tens of millions of single-block reads. The batch is not slow — it is executing the wrong plan.
// resolution steps
- Immediate: pin the known-good plan (SQL plan baseline from the prior plan hash)
- Repair statistics on the skewed column (histogram strategy, or set column stats deliberately)
- Fence the auto-stats job away from pre-batch hours for settlement-critical tables
Composite walkthrough drawn from the Oracle detection-path library — the shape of every diagnosis: symptom, evidence, root cause, resolution. Yours will name your tables.
Path library coverage
What the Oracle detection paths watch
- Wait-event analysis: ASH-pattern paths for the canonical wait classes, run continuously
- Plan stability: plan-hash changes on critical SQL, bind-peeking flips, adaptive-plan reversals
- Undo/redo: ORA-01555 exposure, undo consumption by session, log-file-sync decomposition
- RAC: global-cache wait patterns, interconnect health, instance skew
- Memory: PGA workarea shortfalls, SGA advisories, temp-spill attribution
- Sessions and locking: blocking trees, TX enqueue chains, session-leak signatures
Connect your Oracle — free.
Read-only agent, on-prem, 90 seconds to your first diagnosis. Your first database is free for life — make it the Oracle that hurts.
First database free. For life.
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