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Performance Improvement on Dictionary Views in Oracle 21c

December 8, 2023Nenad Noveljic Leave a Comment

Oracle’s heuristics previously avoided considering fixed tables for Join Predicate Pushdown (JPPD) transformation, leading to suboptimal plans. Enforcing predicate pushing into the view with the PUSH_PRED hint was a workaround. Oracle addressed this in the 21c release, evaluating fixed tables for JPPD. Continue Reading →

21c, cost based optimizer, join predicate push-down (JPPD), Oracle

Bind Variable Length in PL/SQL, C, Java and Python

October 18, 2022Nenad Noveljic 4 Comments

PL/SQL, C, Python and Java handle bind variable length differently. As a consequence, different execution plans could be generated when the same query runs from different programming languages.
Continue Reading →

cost based optimizer, Oracle

ORA-07445 [__intel_avx_rep_memcpy()] During a Rowset Operation

October 2, 2022Nenad Noveljic Leave a Comment

Workarounds provided Continue Reading →

ORA-07445, Oracle

OCI Demo Linking Error

September 28, 2022Nenad Noveljic Leave a Comment

An error in the make file with an easy fix. Continue Reading →

linker, Oracle

A Data Model Fix for Suboptimal Semi-Join and Anti-Join Cardinality Estimates

September 7, 2022Nenad Noveljic Leave a Comment

Analysis of dataset properties leading to a bad performance problem with a simple fix. Continue Reading →

cost based optimizer, data modelling, Oracle

Undocumented Implicit Partition Statistics Gathering

August 26, 2022Nenad Noveljic 1 Comment

A boundary condition where subpartition statistics gathering can also trigger partition statistics Continue Reading →

Oracle, Statistics

Changing OSWatcher User

July 30, 2022Nenad Noveljic Leave a Comment

Tracing TFA to find out how to change user under under which OSWatcher ist started. Continue Reading →

eBPF, Linux, TFA

Troubleshooting TFA Start

July 18, 2022Nenad Noveljic Leave a Comment

A server crash can prevent a correct TFA start. Continue Reading →

eBPF, TFA

Kernel Memory Leak due to ACFS Snapshots

July 12, 2022Nenad Noveljic Leave a Comment

The case study of troubleshooting a serious kernel memory leak issue caused by a failed ACFS snapshot deletion. Continue Reading →

eBPF, Oracle, slab

slabinfo

July 5, 2022Nenad Noveljic Leave a Comment

Check your /proc/slabinfo permissions if your Oracle OSWatcher isn’t running under root. Continue Reading →

Linux, Oracle, slab

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Recent Posts

  • Performance Improvement on Dictionary Views in Oracle 21c
  • Bind Variable Length in PL/SQL, C, Java and Python
  • ORA-07445 [__intel_avx_rep_memcpy()] During a Rowset Operation
  • OCI Demo Linking Error
  • A Data Model Fix for Suboptimal Semi-Join and Anti-Join Cardinality Estimates
  • Undocumented Implicit Partition Statistics Gathering
  • Changing OSWatcher User
  • Troubleshooting TFA Start
  • Kernel Memory Leak due to ACFS Snapshots
  • slabinfo
  • Troubleshooting ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired
  • WINDOW SORT PUSHED RANK Performance Regression in Oracle 21c

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  • Deadlock Detection | Oracle Scratchpad on Deadlock Caused by Row Cache and Library Cache Locks
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