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Oracle SQL Tuning Expert Series - Understanding Indexes

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Ross Leishman of DWS Ltd presents the principles of Understanding Indexes for SQL Tuning. The presentation includes an entertaining demonstration of Indexes featuring DWS Alumnus Jordan Thomas as a "Buffer Cache". DWS Ltd is a leading publicly listed Australian IT Services company, providing services to blue chip organisations since 1991. With a business philosophy based upon integrity, reliability and professional service delivery, DWS provides end to end IT solutions. www.dws.com.au
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Text Comments (21)
Manjunath Maller (8 months ago)
Excellent Presentation.Cleared a lot of concepts.
Rohit Joshi (8 months ago)
I was once thrown out of oracle interview for telling B tree is Binary Tree... :) Wish the interviewer would have seen this and knew I am not alone...
Balgovind Tiwari (1 year ago)
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Prachi Deshmukh (1 year ago)
Excellent Video. I could able to solve my performance problem with this information. Thanks Ross
MGM L (2 years ago)
In Q&A, talking about network latency as a reason for performance degradation reading from disks, because the data has to go back and forth - Even if the data has to be read from the buffer cache where the buffer cache is also in the server memory and hence there is a round trip (network latency). So, doesn't it just come down to only the quick access from memory versus relatively slow access from the disk? Because, there is network latency in both? Thanks
Ross Leishman (2 years ago)
Hi MGM L. I'm not sure I understand your question. Are you saying the cost of a round trip to memory is the same as Network Latency. I'm no hardware geek, so I'm prepared to be shouted down on this, but Memory (RAM) is resident on the machine and directly accessible by the CPU. Latency to pick something out of RAM is vanishingly fast.Disk systems CAN be resident on the machine (like the SSD in my laptop), but are not directly accessible by the CPU. It needs to send a message to the disk controller to find and read data. That round-trip is called (at least I call it) Disk Latency, and it is fast, but nothing like as fast as reading from memory.Enterprise databases don't exist on my laptop. More often than not, their disk storage is NOT resident on the machine - it's on a whole nuther machine. When the database wants something off that disk system, it needs to send a message across the network to that machine, and THAT'S Network Latency - it takes time.
parag goel (2 years ago)
I want to learn your way - in the end you said there will be more presentations in future. Hope you have given them. But sadly, I was not able to find the links in YouTube. Can you help me finding those. Thanks in advance.
parag goel (2 years ago)
Thanks Ross.
Ross Leishman (2 years ago)
There's no more Oracle presentations ... yet. But if you follow the DWS channel, YouTube will let you know when they arrive.
parag goel (2 years ago)
Ross you are awesome. I need more links to your video s
parag goel (2 years ago)
He he he... :)... Yeah, I agree with you. Thanks anyways.
Ross Leishman (2 years ago)
Cheers Parag. If only I could turn kudos into cash :-)
parag goel (2 years ago)
where can I find the link to more presentation s of urs. loads of things to learn from you
Saurabh Mittal (2 years ago)
Thank you Ross! Excellent video, where can I find the video for next session?
Ross Leishman (2 years ago)
It hasn't been made yet. But subscribe to the channel so you don't miss out.
Debabrata Patnaik (2 years ago)
A very elegant presentation. The exercise was perfect and I feel the guy representing Buffer Cache will definitely remember oracle index working for a long long time.
Ross Leishman (2 years ago)
Thanks Debabrata. Yes, the demo worked better than I had any right to expect, mostly thanks to Jordan's sublime comic timing.
Srinivas Narsappa (2 years ago)
what r disadvantage of index
Debabrata Patnaik (2 years ago)
Index has straight impact on the data loads as index has to be rebuild for data loads as specified in the presentation for new data blocks for attributes which are indexed. Be very careful on choosing what to index. If there are multiple index data loads will get impacted as well as those might or might not be used for all sql queries.
Srinivas Narsappa (2 years ago)
good to learn and understand in simple ways
Vitor Olio (2 years ago)
excellent.

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