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Comments
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Howard Wild on
11/12/2008
Great, I liked that one a lot, A second query example showing how the developer gets rid of the second hash match would go a long way demonstrating how to increase performance.
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Great Video
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very clear, further explanation would be usefull, but I guess that's in a pay service?
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Grant Fritchey on
11/12/2008
No, not a pay service. The goal for all the videos I recorded was to give short, sharp, examples, describing individual operators inside execution plans. That's it.
Now, I need to go & start recording longer videos that talk about how to solve or work with or interprate the operators I've presented.
In my spare time...
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John Wilder on
11/12/2008
OK for what was said, but light on the concept overall. I was expecting more information:
a) Why would the optimizer chose a hash match over other join techniques?
b) How do I know that a hash match is being used inappropriately? Is the only factor that the data sets are about the same size?
c)Is there information available about the values being hashed and the size of the hash table?
d)Are there things that can be done to make a hash match perform more efficiently?
Also - while I understand hashing many people don't and I think some sort of simple graphic showing the translation of business values to hash values in a hash table would help explain the concept.
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thomas taylor on
11/12/2008
And
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Jonathan Winer on
11/12/2008
Great intro to a topic, but lacking any real meat. For example 1) what clauses in the query are responsible for these two hash matches. 2) what can be done to the existing query and underlying schema to remove the hash matches or reduce their costs.
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Robert Neal on
11/12/2008
Excellant video but I wanted more information
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I really appreciated this video and would love to see more on the explanation of the types of joins SQL performs. Thanks for this!
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I really appreciated this video and would love to see more on the explanation of the types of joins SQL performs. Thanks for this!
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Carla Wilson on
11/12/2008
Thanks for opening my eyes to the hash match in execution plans. I checked a couple of my joins that I thought were straight-forward and was surprised to see the hash match used frequently - even for things I tought were indexed. I would like to see more information about how the optimizer uses different techniques. Sounds like indexing is key.
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Great explanation, some are more visual learners and an example of a couple of tables may help. Also an example of how a missing index or Where Clause can affect SQL efficiency when it uses HASH Match. Thanks!
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James Mount on
11/12/2008
This actually explained what a hash match is! Thank you!
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Ahmad Elayyan on
11/12/2008
Thanks A lot for this Video but the voice was not clear.
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maybe just a bit longer to explain more
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the stated point here is that "a missing or incorrect index" or one (predicate) such that "index cannot be used"
But... it would be a much improved instructional video to increase its length and go back to the t-sql and examine the indexes and prove or argue your thesis
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Great
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excellent video
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I am somewhat more clear on what a hash match join operator is now, but I still don't feel like I quite get it. Perhaps some example on how to create it would have helped.
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Nice explanation about hash match...
But I think you should talk a little bit more about what we could do to avoid those inneficiente joins as you say.
Thanks.
Marco
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Good work guys. Quick and useful.
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Good work guys. Quick and useful.
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Grant Fritchey on
11/25/2008
For all those that want more, I'm planning some expanded videos. They won't be available any time soon (my "free time" is a bit busy at the moment). I'll focus initially on how indexing changes execution plans. They will be longer.
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Sweet, you described the word "Hash Join" extremely well in plain simple words.
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should have been longer, perhaps illustrating how adding an index could eliminate the hash match in the inefficient scenario described...
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It would be good to get into a little more detail behind the hash match and demonstrate how it may be able to be corrected.
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Not enough information.
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Would have liked to see more about how to fix the bad hash match but it did explain some thing and gave me some ideas what to go after
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Congratulations on the MVP! Thanks for all the support you offer to the community!
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I would have liked to see how to trouble shoot the issue
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Help to understand.
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Its very useful
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Very good intro, I need to learn more on my own now.
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Sound does not work.
Where is the transcript?
Why do I need a STUPID video, when I can read the transcript in less time???????????
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