parallel recovery push change
A stuck nanosleep call impairs a parallel recovery process. The affected parallel recovery process spends 100% of its time in the undocumented parallel recovery push change wait event. Continue Reading
Author: Nenad Noveljic
A Case Study: How Advanced Queuing and Alerts Prevented Private Strands Usage
A process waiting on an Advanced Queue or alert allocates an in-memory undo buffer and holds it as long as it’s waiting, even when there aren’t any incoming mesages. Many such processes can prevent private strands usage.
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Transaction start_time Internals
Troubleshooting wrong v$transaction.start_time entries. Undocumented internals on how Oracle populates x$ktcxb. Continue Reading
OR-Expansion of Subqueries – Limitations
How to overcome the limitations of expansion of OR-subqueries in Oracle 19c. Continue Reading
Lateral View Improvement in Oracle 19c
Suboptimal handling of lateral views has improved in Oracle 19c. Continue Reading
Redo Copy Latch Contention 2: MTTR Advisor
MTTR advisor data gathering can cause redo copy latch contention on servers with many CPUs. Checkpoint queue internals. An example of analyzing a compiled function in a proprietary code without disassembling it. Continue Reading
Tracing Latches: Redo Copy Contention
Tracing latches with OS tools, case study: redo copy contention caused by a logon storm Continue Reading
Suboptimal Sort Calculation
Beware of the suboptimal sort cost calculation in SQL Server. Comparison with Oracle included. Continue Reading
Tracing Library Cache Locks
Tracing Library Cache Locks with DTrace Continue Reading
Deadlock Caused by Row Cache and Library Cache Locks
Reproducing Oracle deadlock bug with debugger Continue Reading