DBA AWR Latch by Time – Oracle EBS SQL Report
Oracle E-Business Suite SQL report from the Enginatics Library powered by Blitz Report™. Oracle EBS module: Database Administration · all Database Administration reports
Overview
Latch contention wait time history. Each row shows the system-wide latch contention wait time per latch name of one AWR snapshot interval to identify high latch contention at specific times.
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Report Parameters
Date From, Date To, Diagnostic Pack enabled, Container Data
Oracle EBS Tables Used
dba_hist_snapshot, dba_hist_latch
Report Categories
Related Reports
DBA AWR Latch Summary, DBA AWR CPU vs Wait Time Summary, DBA AWR PGA History, DBA SGA+PGA Memory Configuration, DBA AWR Blocking Session Summary, DBA AWR Wait Class by Time, DBA AWR SQL Performance Summary, DBA AWR Wait Event Summary, DBA AWR System Metrics Summary
Running This SQL Without Blitz Report
The SQL source can be run in any SQL client. Some Oracle EBS SQL reports in this library use functions from the utility package xxen_util – install it first. Blitz Report™ adds parameters, Excel output with pivots, scheduling and security on top.
Download & Import Options
| Resource | Link |
|---|---|
| Excel Example Output | DBA AWR Latch by Time 26-Nov-2018 201456.xlsx |
| Blitz Report™ XML Import | DBA_AWR_Latch_by_Time.xml |
| SQL Source | DBA AWR Latch by Time.sql |
| Full Report on Enginatics | www.enginatics.com/reports/dba-awr-latch-by-time/ |
Executive Summary
The DBA AWR Latch by Time report analyzes low-level serialization mechanisms called “Latches”. Unlike locks (which protect data), latches protect memory structures in the SGA (System Global Area). High latch contention indicates that too many processes are trying to access the same memory structure simultaneously, leading to CPU spikes and “spinning”. This report tracks latch wait times over time.
Business Challenge
- CPU Spikes: Latch contention often manifests as high CPU usage because processes “spin” (burn CPU) while waiting for a latch.
- Concurrency Bottlenecks: Identifying specific times when memory access becomes a bottleneck (e.g., “Cache Buffers Chains” latch during a batch run).
- Scalability Limits: Latch contention is often the limiting factor in how many concurrent users a system can support.
Solution
This report shows the wait time for each latch type per AWR snapshot.
Key Features:
- Time-Series View: Shows how latch contention evolves over the day.
- Latch Identification: Identifies the specific latch name (e.g., “shared pool”, “library cache”).
Architecture
The report queries DBA_HIST_LATCH.
Key Tables:
DBA_HIST_LATCH: Historical latch statistics.DBA_HIST_SNAPSHOT: Snapshot timing.
Impact
- Deep Tuning: Helps DBAs diagnose complex internal contention issues that standard SQL tuning cannot fix.
- Application Design: Can point to design flaws (e.g., lack of bind variables causing “library cache” latch contention).
- System Health: Ensures the internal memory management mechanisms are functioning smoothly.
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