Oracle

fritshoogland's picture

An investigation into exadata

This is an investigation into an half rack database machine (the half rack database machine at VX Company). It’s an exadata/database V2, which means SUN hardware and database and cell (storage) software version 11.2.

I build a table (called ‘CG_VAR’), which consists of:
- bytes: 50787188736 (47.30 GB)
- extents: 6194
- blocks: 6199608

The table doesn’t have a primary key, nor any other constraints, nor any indexes. (of course this is not a real life situation)

No exadata optimisation

At first I disabled the Oracle storage optimisation using the session parameter ‘CELL_OFFLOAD_PROCESSING’:
alter session set cell_offload_processing=false;

Then executed: select count(*) from cg_var where sample_id=1;
The value ’1′ in the table ‘CG_VAR’ accounts for roughly 25%.

Execution plan:

oraclebase's picture

SQL Developer and MS SQL Server…

This afternoon I’ve been cleaning up some data in an SQL Server database. I decided to use SQL*Developer to connect to SQL Server by following this post.

I made liberal use of the following tip when dealing with TEXT and NTEXT types.

The joys of dealing with multiple engines…

Cheers

Tim…

James Morle's picture

SaneSAN2010: Serial to Serial – When One Bottleneck Isn’t Enough

I was recently looking into a storage-related performance problem at a customer site. The system was an Oracle 10.2.0.4/SLES 9 Linux system, Fibre Channel attached to an EMC DMX storage array. The DMX was replicated to a DR site using SRDF/S.

The problem was only really visible during the overnight batch runs, so AWR reports were the main source of information in diagnosis. In this case, they were more than sufficient, showing clear wait spikes for ‘free buffer waits’ and ‘log file parallel write’ during the problematic period. They were quite impressive, too – sixteen second latencies for some of the writes.

James Morle's picture

Sane SAN 2010 – Introduction

This year at the UKOUG Conference in Birmingham, acceptance permitting, I will present the successor to my original Sane SAN whitepaper first penned in 2000. The initial paper was spectacularly well received, relatively speaking, mostly because disk storage at that time was very much a black box to DBAs and a great deal of mystique surrounded its operation. Well, nothing much has changed on that front, so I figured it was very much time to update/rewrite the paper for modern technology and trends and try to impose my occasionally humble opinion on the reader </p />
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fritshoogland's picture

OakTable member!

Just like Tim Hall I was nominated and approved as a member of the OakTable network. I am very happy to have been accepted to a group of such gifted individuals!

oraclebase's picture

OakTable…

I was recently nominated and approved as a member of the OakTable Network .

Do you ever get that feeling that one day people are going to realize you don’t have a clue what you are talking about? I think that day just got a little closer. :)

Cheers

Tim…

oraclebase's picture

Wirth’s Law…

I was scooting around the net and I stumbled on a reference to Wirth’s Law and had a flashback (not Nam related) to a conversation I had about 14 years ago with my boss at the time. We were setting up the kit for a new automated warehouse solution (Oracle 7, HP 9000s and ServiceGuard if I remember correctly) and he said something along the lines of, “Why is it that for each customer we buy faster and more expensive computers, yet they take the same length of time to produce the results?”

The answer was pretty simple in that case. We were refurbishing the existing (fairly simple) warehouse as well as adding a completely new one. We were replacing some AVGs with a very complex conveyor layout, which required some difficult routing decisions. The basic “find me a space in the warehouse” decisions were replaced by pretty complex searches that had to take account of conveyor routing, system load and potentional sorting (and defragmentation) of the content in the warehouse. The customer needed a highly available solution, hence the use of ServiceGuard, so we more than doubled the hardware and software costs for no perceivable performance improvement. From the outside looking in it seemed like nothing had changed. It was still, “Here’s a pallet, put it in the racking”, but the process required to do that operation efficiently had increased in complexity manyfold.

oraclebase's picture

Fedora 13 and Oracle…

Until a couple of days ago I hadn’t even realized that Fedora 13 was out. I guess that shows how interested I am in Fedora these days. :)

Anyway, I had a play around with it.

Cheers

Tim…

kevinclosson's picture

Do-It-Yourself Exadata-Level Performance! Really? Part IV.

In my post entitled Do-It-Yourself Exadata-Level Performance? Really? I invited readers to visit the Oracle Mix page and vote for my suggest-a-session where I aimed to present on DIY Exadata-level performance. As the following screenshot shows I got a lot of good folks to vote on that. It must have been an interesting sounding topic! Yes, [...]

fritshoogland's picture

Introduction to the Oracle database machine

For those of you who haven’t followed all the Oracle Exadata and database machine information, and want a brief introduction to the database machine: here it is!

The confusion

There is some confusion about ‘exadata’ and ‘the database machine’. If we look at the official product names, ‘Exadata’ is the storage server, and the ‘Database machine’ is the complete boxed machine, including exadata for storage. But…in the real world, in different kinds of papers (technical, advertising) exadata sometimes is used as an alias for the database machine.

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