Tag: I/O
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A new web application for the DBOD service
A new web application for the DBOD service Introduction The DBOD service maintains a web interface allowing “database on demand” users to carry out ordinary tasks without intervention of the administrators. It is with a view to ergonomy, but above all to modularity and scalability, that a complete redesign of this application has been initiated.
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Performance Analysis of a CPU-Intensive Workload in Apache Spark
Performance Analysis of a CPU-Intensive Workload in Apache Spark Topic: This post is about techniques and tools for measuring and understanding CPU-bound and memory-bound workloads in Apache Spark. You will find examples applied to studying a simple workload consisting of reading Apache Parquet files into a Spark DataFrame. Why are the topics discussed here relevant
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Linux BPF/bcc for Oracle Tracing
Linux BPF/bcc for Oracle Tracing Topic: In this post you will find a short discussion and pointers to the code of a few sample scripts that I have written using Linux BPF/bcc and uprobes for Oracle tracing. Previous work and motivations Tools for dynamic tracing are very useful for troubleshooting and internals investigations of Oracle
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Heat Map Visualization of Latency Histograms for NetApp C-Mode
Heat Map Visualization of Latency Histograms for NetApp C-Mode Topic: This post is about collecting and visualizing I/O latency histograms for NetApp filers in C-mode. Motivations: The drill down of I/O latency is an important technique for troubleshooting and benchmarking storage. Average latency values can hide details of what is happening on the storage. Think
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Latest updates to PerfSheet4, a tool for Oracle AWR data mining and visualization
Latest updates to PerfSheet4, a tool for Oracle AWR data mining and visualization Topic: This post is about the latest updates to PerfSheet4 v3.7 (February 2015). PerfSheet4 is a tool aimed at DBAs and Oracle performance analysts. It provides a simplified interface to extract and visualize AWR time series data using Excel pivot charts. Why
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Scaling up Cardinality Estimates in 12.1.0.2
Scaling up Cardinality Estimates in 12.1.0.2 Topic: Counting the number of distinct values (NDV) for a table column has important applications in the database domain, ranging from query optimization to optimizing reports for large data warehouses. However the legacy SQL method of using SELECT COUNT (DISTINCT <COL>) can be very slow. This is a well
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Flame Graphs for Oracle
Flame Graphs for Oracle Topic: This post is a hands-on introduction to using on-CPU Flame Graphs for investigating Oracle workloads. This technique is about collecting and visualizing sampled stack trace data to analyze and troubleshoot Oracle processes at the OS level (in particular applied to Linux). Motivations: The techniques and tools described here can be
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A Closer Look at CALIBRATE_IO
A Closer Look at CALIBRATE_IO Topic: This blog entry is about investigating Oracle’s DBMS_RESOURCE_MANAGER.CALIBRATE_IO Spoiler: For quantitative analysis of storage performance and in particular for measuring random read I/O in Oracle, I’d rather advise the use tools that allow generating test workloads in a controlled manner, in a way that can be understood and measured