Developer Interview (#DI15) with Niko Köbler (@dasniko) Java EE and Node.js Performance

Developer interview Friday. Today it is my pleasure to welcome Niko Köbler (@dasniko). We meet a couple of times before and I love following his ramblings about JavaScript on the server side. I talked to him about why and how he came in contact with server side JavaScript in general and made him show a little more about his recent performance test, that he ran against RESTFUL backends (WIldFly and node.js). For (more...)

DBMS_INMEMORY_ADVISOR

When you follow the Oracle in-memory / optimizer team, then you have probably seen this…

Merge, Right?


"There are no wrong roads to anywhere."
 - Norton Juster, The Phantom Tollbooth 

Oracle can do some, well, strange things when fixing issues caused by the optimizer. For 10g releases up to 10.2.0.x Oracle chose to silently ignore a message and eliminate an outer join on the MERGE statement under certain conditions. Let’s examine this and see exactly what Oracle implements.

Occasionally in a 10046 trace file generated from 10g releases (more...)

ADF BC Range Paging and REST Pagination

In this post I would like to explore and integrate two thing - ADF BC Range Paging and REST service pagination. It would inefficient to retrieve entire set of data in the REST service, ideally should be available option to specify number of rows and range number to fetch. ADF BC allows to query VO in Range Paging mode - SQL query will be constructed with row numbers, to query data in certain range of (more...)

255 columns

Here’s a quick note, written and some strange time in (my) morning in Hpng Kong airport as I wait for my next flight – all spelling, grammar, and factual errors will be attributed to jet-lag or something.

And a happy new year to my Chinese readers.

You all know that having more than 255 columns in a table is a Bad Thing ™ – and surprisingly you don’t even have to get to 255 to (more...)

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 PerfSheet4: PerfSheet4 is aimed at querying and displaying time-series data from AWR repository tables. This is very a rich source of information to analyze database workloads and trends in the context of performance analysis or (more...)

Binary search – is it still most optimal?

If you have a sorted collection of elements, how would you find index of specific value?
"Binary search" is likely to be your answer.
Algorithms theory is teaching us what binary search is most optimal algorithm for this task with log(N) complexity.
Well, hash table can do better, if you need to find key by exact match. In many cases, though, you have reasons to have your collection sorted, not hashed.

On my job, I'm (more...)

MAF 2.1 Alta Mobile UI and Oracle Mobile Suite

This post is about Alta Mobile UI and MAF 2.1. I was using Oracle Work Better mobile application as a reference, along with Alta Mobile UI Design Guidelines. This is based on my previous posts about Oracle Mobile Suite and MAF 2.1 integration, read more here - Oracle Mobile Suite - Web Service Performance Optimisation with Result Caching. You could also use Alta UI 12c with regular ADF Web applications, check more here (more...)

To N or Not to N, is SYS_OP_C2C the Question; Oracle NVARCHAR Slow?

February 8, 2015 I was recently contacted about an odd performance issue with a software product named TDM, where certain SQL statements submitted to an Oracle 9.2.x database required roughly 30 seconds to execute when a nearly instantaneous response was expected.  The person who reported the issue to me provided a sample SQL statement that […]

OBIEE Monitoring and Diagnostics with InfluxDB and Grafana

In this article I’m going to look at collecting time-series metrics into the InfluxDB database and visualising them in snazzy Grafana dashboards. The datasets I’m going to use are OS metrics (CPU, Disk, etc) and the DMS metrics from OBIEE, both of which are collected using the support for a Carbon/Graphite listener in InfluxDB.

The Dynamic Monitoring System (DMS) in OBIEE is one of the best ways of being able to peer into the internals (more...)

Functions & Subqueries

I think the “mini-series” is a really nice blogging concept – it can pull together a number of short articles to offer a much better learning experience for the reader than they could get from the random collection of sound-bites that so often typifies an internet search; so here’s my recommendation for this week’s mini-series: a set of articles by Sayan Malakshinov a couple of years ago comparing the behaviour of Deterministic Functions and Scalar (more...)

Oracle Mobile Suite – Web Service Performance Optimisation with Result Caching

One of the main advantages of Oracle Mobile Suite - Service Bus and SOAP/REST web service transformation (more here - Oracle Mobile Suite Service Bus REST and ADF BC SOAP). In addition you will get very nice performance improvement, there is out of the box caching for Web Service resultset with Coherence. I'm going to demonstrate how it works, all out of the box - really simple.

You could define caching for external service (more...)

How Can I Compress Thee


“You can swim all day in the Sea of Knowledge and not get wet.” 
― Norton Juster, The Phantom Tollbooth 

In previous posts compression options have been discussed, and now it’s time to see how Oracle performs basic compression. It isn’t really compression, it’e de-duplication, but it does result in space savings for data that won’t be modified after it’s ‘compressed’. Let’s look at how Oracle saves space with your data.

Oracle de-duplicates the (more...)

Bind peeking and session cached cursor

Bind peeking is a nice feature in Oracle to have many optimized plans for an SQL for various bind values.  DBAs believe that bind peeking happens during a soft parse which will identify an alternate plan. Why do I say that?

 

Hard Parse: Parsing first time, nothing exists to bind peek

 

Soft Parse :  SQL cursor is existing and executing not the first time.  Under the soft parse, bind peeking (more...)

Blog update!

Hi everyone!

This blog hasn’t seen any updates since over a year now and I do apologize for that. However, the reason for that is simple. Last year I’ve decided to take one a new project. But before I was going to tell everybody about it I wanted to make sure that I also really got the time to do so. In the meantime I got the confidence that the project will succeed and that (more...)

New Version Of XPLAN_ASH Utility – In-Memory Support

A new version 4.21 of the XPLAN_ASH utility is available for download. I publish this version because it will be used in the recent video tutorials explaining the Active Session History functionality of the script.

As usual the latest version can be downloaded here.

This is mainly a maintenance release that fixes some incompatibilities of the 4.2 version with less recent versions (10.2 and 11.2.0.1).

As an extra however, (more...)

Cluster Cache Coherency in EM12c

January is winding down and RMOUG Training Days 2015 is just around the corner, taking up much of my after work hours.

With that, we are going to discuss a great performance console in the EM12c cloud control-  Cluster Cache Coherency.

Cluster Cache Coherency

Optimization for an Oracle Real Application Cluster, (RAC) can be a daunting tasks for those that aren’t familiar with some of the most common issues to look for.  Although many (more...)

Bitmap Counts

In an earlier post (not very serious) post about count(*) I pointed out how the optimizer sometimes does a redundant bitmap conversion to rowid when counting. In the basic count(*) example I showed this wasn’t a realistic issue unless you had set cursor_sharing to force (or the now-deprecated similar). There are, however, some cases where the optimizer can do this in more realistic circumstances and this posting models a scenario I came across a few (more...)

enq: TM – contention due to parallel DML and foreign keys

This is a write-up of an issue I recently posted to the OTN discussion forum (https://community.oracle.com/message/12798407). I thought the associated test case was useful in demonstrating the issue, so is captured here for future reference. There were some useful replies to the OTN post, confirming my suspicions.

The test was performed using Oracle Enterprise Edition 11.2.0.3.0 on Linux.

Problem statement

A parallel delete blocks insert into dependent (more...)

The info in OTHER_XML of view DBA_HIST_SQL_PLAN

I had some time to spend, killing time, and thought about something that was “on…