Data Pump’s amazingly useful METRICS=Y and LOGTIME=ALL parameters

Now that I am back from OpenWorld, I will hijack the Upgrade blog while Mike is traveling. Thank you to everybody who came to our presentations or stopped at the demo booth to chat last week. We had a great many conversations, and we always learn from talking to customers! One of the common questions about Data... [Read More]

Spark 2.0 Performance Improvements Investigated With Flame Graphs

Topic: This post is about performance optimizations introduced in Apache Spark 2.0, in particular whole-stage code generation. A test case is introduced and investigated with diagnostic tools.


Introduction: performance troubleshooting of a slow query using parallel query execution in a Hadoop cluster

The idea for this post comes from a performance troubleshooting case that has come up recently on our database services. It started with a user reporting slow response time from a query (more...)

Oracle Database Cloud (DBaaS) Performance Consistency – Part 3

This is the third part of this installment, comparing the performance consistency of the DBaaS cloud offering with a dedicated physical host. This time instead of burning CPU using logical I/O only (see part 2) the test harness executes a SQL statement that has to perform physical I/O mostly, and to be more precise this round is a read-only test, so doesn't include any modification to data (except the logging and any other background (more...)

EM13c: Performance Tuning Access to Read Only Administrators

About six months ago, when I was in the OUGN Spring Conference, someone asked me how they can let developers access to performance tuning pages on Enterprise Manager Cloud Control 13c. He said that they granted full administrator privileges to the developers so they could access the performance page but it’s not acceptable. He also mentioned that they didn’t need to grant full administration privilege to the developers’ EM users while they were using (more...)

Set all WebLogic log levels to “Inherit” via WLST

Logging is a very useful feature of WebLogic.

Unfortunately the log levels, which are set after a clean install of WebLogic or some of the Fusion Middleware product creates a lot of noise and therefore it costs I/O performance.

Additional after analyzing an issue with logging often resetting the log level is forgotten.

Here you get a script to reset the log levels at regular intervals or after a trace session.

#!/usr/bin/python
execfile('get_environment.py')
 (more...)

Adaptive Cursor Sharing Fail

Here is another example (besides the fact that Adaptive Cursor Sharing only gets evaluated during a PARSE call (still valid in 12c) and supports a maximum of 14 bind variables) I've recently come across at a client site where the default implementation of Adaptive Cursor Sharing fails to create a more suitable execution plan for different bind variable values.Broken down to a bare minimum the query was sometimes executed using non-existing values for a (more...)

Nested Loop Join Physical I/O Optimizations

Having done my mini-series on Nested Loop join logical I/O optimizations a while ago I unfortunately never managed to publish anything regarding the Nested Loop join physical I/O optimizations, which are certainly much more relevant to real-life performance.Therefore the main purpose of this blog post is to point you to Nikolay Savvinov's (whose blog I can recommend in general) great mini-series covering various aspects of these optimizations:Part 1Part 2Part 3Summary (more...)

Oracle Database Cloud (DBaaS) Performance Consistency – Part 2

This is the second part of this installment, comparing the performance consistency of the DBaaS cloud offering with a dedicated physical host. This time instead of burning CPU using a trivial PL/SQL loop (see part 1) the test harness executes a SQL statement that performs logical I/O only, so no physical I/O involved.

In order to achieve that a variation of Jonathan Lewis' good old "kill_cpu" script got executed. In principle each thread performed (more...)

Comparing Columns Containing NULL Values

Prompted by a (not really that) recent discussion on the OTN forum I've decided to publish this note.Sometimes you have the task of comparing column values and handling the NULL value cases correctly makes this rather cumbersome for columns that are allowed to be NULL.The "official" SQL way of comparing two column values and to find out whether they are equal or not - under the assumption that having NULL in both columns (more...)

New Version Of XPLAN_ASH Utility

A new version 4.23 of the XPLAN_ASH utility is available for download.

As usual the latest version can be downloaded here.

This version comes only with minor changes, see the change log below.

Here are the notes from the change log:

- Finally corrected the very old and wrong description of "wait times" in the script comments, where it was talking about "in-flight" wait events but that is not correct. ASH performs a "fix-up" (more...)

ADF BC Range Paging and ADF UI Table Pagination Use Case

ADF UI table pagination and ADF BC range paging sounds like a perfect combination. But to make it work perfect, a bit of extra effort is required. In the case of search/edit implementation, it can't remember updated record when navigating back to search screen (VO runs with Range Paging and UI table is displayed with pagination). I will explain how to solve it and show how to keep UI table displaying current page and prevent (more...)

UKOUG Slides – Forms, ADF and JET a Non-Aggression Pact

Florin Marcus was presenting topic on Forms modernization during UKOUG Development SIG seminar in London. Session was based on our production experience from recent Forms modernization project to ADF 12c and Alta UI.

Highlights:

- Who integrates Forms and ADF?

- Java Plugin to be Discontinued. Consequences for Oracle Forms.

- Why Yet Another Web Framework? Oracle JET.

- Forms and ADF and JET - Business Integration Patterns

- Forms Developer's perspective: life after learning (more...)

Oracle Database Cloud (DBaaS) Performance Consistency

As Oracle ACE Director I got an extended trial license for Oracle's Cloud offerings, in particular the "Database as a Service" offering. As part of the (ongoing) evaluation I try to get an idea how consistent the performance of such an service is, which might be one of the concerns one might have when considering cloud offerings in general.

For my tests I've set up a 11.2.0.4 single instance database using "4 (more...)

Unified Auditing – some insights

Oracle 12c Unified Auditing is a brand new feature in the latest Oracle version which consolidates database level auditing records into a single location. DBAs can access the audit information from the view UNIFIED_AUDIT_TRAIL for all kind audit records, and they are

SQL> select distinct COMPONENT from all_unified_audit_actions;

COMPONENT
----------------------------------------------------------------
Direct path API
RMAN_AUDIT
Database Vault
XS
Label Security
Datapump
Standard
FineGrainedAudit

8 rows selected.

UNIFIED_AUDIT_TRAIL is a view owned by SYS and a public (more...)

More on CSS selector performance in Oracle APEX

Last month I wrote a post about CSS performance, including some performance test results.

I recently encountered this brilliant post on Medium that describes some best practices for CSS.

While APEX does a lot of this for you, I think it's worth a read by all developers. Even applying basic naming conventions can make code easier to read and understand.

There was also a section on performance that described an issue that my previous (more...)

Hotsos 2016 Recap

I wanted to go to Hotsos Symposium for quite some time, having heard so many great topics from there for years. And every time I was a bit lazy to think about what I can talk about. Apparently I thought that everything I know is well covered elsewhere, so why would I be accepted. Plus all these complexities of budget, getting a visa, travel arrangements, jet lag, and personal matters in between. Last year, when (more...)

Oracle Management Cloud – Log Analytics

In last overview post I will give you a first glance of the Oracle Management…

Oracle 12c Caching and In Memory Databases

A few weeks ago, I was asked to give a private session about In-Memory database vs. traditional persistent databases. I created an hour-long session explaining the basics of database systems, how in-memory systems work, and when to use each of the systems.

One of the questions I got (and answered) was about persistent (regular) database cache mechanism – and I felt this is a good opportunity to write about Oracle 12c new feature – the (more...)

On CSS/jQuery Selector Performance

My post describing the use of a simple selector identifying page spinners was originally going to be about performance, then I learned something I found very interesting.

I likened what I learned to Tom Kyte's essay (Asktom->Resources->Presentations->FalseKnowledge.htm) on Correlation vs Causation. The essence was that things change over time, and we can't always trust authorities on the topic, and we must always test in our own environments. This aligns with skepticism in general, and (more...)

Improving PL/SQL performance in APEX

One of the simplest tuning techniques to encapsulate PL/SQL used in APEX within packages, minimising the size of anonymous blocks. This applies to any PL/SQL within the page, including computations, processes, plugins, dynamic actions, validations, shortcuts and dynamic PL/SQL regions.

This change can make a big impact in the execution time of PL/SQL as it's processed at compile time instead of interpreted at runtime.

Plug-ins can be wonderful black boxes and consumers may not care (more...)