DBA AWR Wait Class by Time – Oracle EBS SQL Report

Oracle E-Business Suite SQL report from the Enginatics Library powered by Blitz Report™.

Overview

Non idle session wait times by wait class over time. Each row shows the system-wide wait time per wait class of one AWR snapshot interval to identify unusual wait events that occured at specific times. Use the Session Type parameter to restrict either to foreground, background or all server processes.

To see data in this report based on dba_hist_system_event, set the following: alter session set container=PDB1; alter system set awr_pdb_autoflush_enabled=true;

https://www.enginatics.com/blog/updated-dba-awr-blitz-reports-now-work-with-plugglable-databases/

Report Parameters

Date From, Date To, Session Type, Diagnostic Pack enabled, Container Data

Oracle EBS Tables Used

dba_hist_snapshot, dba_hist_system_event

Report Categories

Diagnostic Pack, Enginatics

Related Reports

DBA AWR Wait Event Summary, DBA AWR Blocking Session Summary, DBA AWR System Metrics Summary, DBA SGA+PGA Memory Configuration, DBA AWR CPU vs Wait Time Summary, DBA AWR System Time Percentages, DBA AWR PGA History, DBA AWR Latch Summary, DBA AWR SQL Performance Summary

Running This SQL Without Blitz Report

Some Oracle EBS SQL reports in this library require functions from the utility package xxen_util. Install it before running the SQL directly against your Oracle EBS database.

Download & Import Options

Resource	Link
Excel Example Output	DBA AWR Wait Class by Time 22-Dec-2025 083647.xlsx
Blitz Report™ XML Import	DBA_AWR_Wait_Class_by_Time.xml
Full SQL on Enginatics	www.enginatics.com/reports/dba-awr-wait-class-by-time/

Executive Summary

This report provides a comprehensive analysis of non-idle session wait times categorized by wait class over a specified time range. It is a critical tool for Database Administrators (DBAs) to identify system-wide performance bottlenecks and understand the distribution of database time across different activity types such as I/O, Concurrency, or Application logic.

Business Challenge

• Performance Degradation: Difficulty in pinpointing the exact time periods when database performance suffers.
• Root Cause Analysis: Challenges in distinguishing between I/O-bound, CPU-bound, or contention-related issues.
• Capacity Planning: Lack of historical data trends to forecast future resource requirements.

The Solution

The DBA AWR Wait Class by Time Blitz Report addresses these challenges by:

• Time-Series Visualization: Presenting wait class data per AWR snapshot interval, allowing for precise correlation with reported slow periods.
• Drill-Down Capabilities: Enabling users to isolate specific wait classes (e.g., “User I/O”) to see their impact over time.
• Pluggable Database Support: Fully compatible with Oracle Multitenant architecture, allowing analysis at the PDB level.

Technical Architecture

The report queries the Oracle Automatic Workload Repository (AWR) tables, specifically DBA_HIST_SNAPSHOT and DBA_HIST_SYSTEM_EVENT. It aggregates the TIME_WAITED_MICRO metric by WAIT_CLASS for each snapshot interval. The logic handles the delta calculation between snapshots to show the wait time incurred during each specific interval rather than cumulative totals.

Parameters & Filtering

• Date From / Date To: Defines the time window for the analysis.
• Session Type: Filters data for ‘Foreground’, ‘Background’, or ‘All’ sessions. Foreground is typically most relevant for user experience.
• Container Data: For multitenant environments, allows selection of specific containers.

Performance & Optimization

• Date Range: Keep the date range focused (e.g., 1-2 days) for high-resolution analysis, as AWR data can be voluminous.
• Snapshot Interval: Ensure AWR snapshot intervals are appropriate (typically 15-60 minutes) for the level of granularity required.

FAQ

• Q: Why do I see no data for my PDB?
  • A: Ensure that awr_pdb_autoflush_enabled is set to true and you are connected to the correct container.
• Q: What is “DB CPU”?
  • A: While not a “wait class” in the traditional sense, this report often includes CPU time to provide a complete picture of DB time.

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