Troubleshooting ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired
Using system dump, ASH and data dictionary to find the blocker when ORA-00054 was raised Continue Reading
Author: Nenad Noveljic
WINDOW SORT PUSHED RANK Performance Regression in Oracle 21c
New optimization causing severe performance degradation. It can be switched off with the fix control. Continue Reading
Workaround for Non-Functioning uretprobes with Oracle Database Software
Oracle database software breaks uprobes and uretprobes. The workaround for uprobes is well known – adding an offset to the function entry. This article explains how to emulate uretprobes with uprobes as a workaround. Continue Reading
killsnoop Limitation
The current implementation of the eBPF bcc tool killsnoop doesn’t capture signals sent by the tgkill() system call. Continue Reading
oradebug request completion
Exploring the internals of the undocumented Oracle wait event “oradebug request completion” with eBPF. An example of an off-CPU analysis. Continue Reading
Perilous New Undocumented Tracing Feature in Oracle 21c
Database writer performance impaired by sudden debug trace. Continue Reading
Failed Shared Pool Memory Allocation for LOB Inserts
Insert LOB might require a shared pool memory allocation, which can fail. The problem is more likely to happen with larger block sizes. Oracle has an undocumented event for tracing LOB insert internals. Continue Reading
NVL Cardinality in Oracle 21c
Reasons for not using NVL for filtering NULL values. Join cardinality estimate improvement in Oracle 21c. Continue Reading
Data Loss After Plugging a PDB
ORA-00600 [25027] in PDB. Tracing buffer reads. kcbgtcr Oracle C function. Continue Reading
ORA-00600 on Materialized View Refresh
Oracle internals for understanding cryptic error messages during materialized view refresh Continue Reading