February 14, 2011 at 10:37 am
Comments posted to this topic are about the item Stairway to SQL Server Indexes: Step 6, Bookmarks
June 8, 2011 at 10:59 am
Thanks for the great article David!
From the article:
Therefore, each row in a database, at any given point in time, can be identified by three numbers; file number - page number - row number. This identifying composite of three numbers is called the row id, usually shortened to RID. Most tools that display SQL Server internals information will display these three numbers separated by colons (instead of hyphens). So the 12th row on the 77th page of file 1 would have a RID of 1:77:12.
You explained why SQL Server will use the RID as the Bookmark in a Heap's non-clustered index but how much space does the RID actually occupy on those index entries? i.e. is the RID comprised of 3 separate INTs and are they stored as such, using 12 bytes on each index entry?
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato
August 3, 2011 at 2:59 am
I see very little of value in this article. The readers are ever so slightly better informed after reading it, but have acquired no useful information. In fact if your conclusions, or lack thereof, are to be believed no decisions should be altered based on the entire topic. As such wouldn't it have been better not to publish it and thus save us all the time spent reading it? This strikes me as the sort of irrelevant waffle published by academics that gives academia a bad name.
Before your next article please try to establish that the topic is worth reading about before writing about it.
August 3, 2011 at 6:00 am
opc.three (6/8/2011)
Thanks for the great article David!From the article:
Therefore, each row in a database, at any given point in time, can be identified by three numbers; file number - page number - row number. This identifying composite of three numbers is called the row id, usually shortened to RID. Most tools that display SQL Server internals information will display these three numbers separated by colons (instead of hyphens). So the 12th row on the 77th page of file 1 would have a RID of 1:77:12.
You explained why SQL Server will use the RID as the Bookmark in a Heap's non-clustered index but how much space does the RID actually occupy on those index entries? i.e. is the RID comprised of 3 separate INTs and are they stored as such, using 12 bytes on each index entry?
I later learned the RID is 8 bytes.
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato
August 3, 2011 at 6:09 am
Steve.Cornelius (8/3/2011)
I see very little of value in this article. The readers are ever so slightly better informed after reading it, but have acquired no useful information. In fact if your conclusions, or lack thereof, are to be believed no decisions should be altered based on the entire topic. As such wouldn't it have been better not to publish it and thus save us all the time spent reading it? This strikes me as the sort of irrelevant waffle published by academics that gives academia a bad name.Before your next article please try to establish that the topic is worth reading about before writing about it.
Why so harsh Steve? It's a "Stairways" article. All writers must consider their target audience. I thought the article was a great primer on bookmarks, indexes and heaps. The three guidelines laid out regarding choosing a clustering key are critical to remember. Even veterans can use some re-enforcement of the fundamentals from time to time. I thought the article was great!
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato
August 3, 2011 at 6:40 am
Why so harsh Steve? It's a "Stairways" article. All writers must consider their target audience. I thought the article was a great primer on bookmarks, indexes and heaps. The three guidelines laid out regarding choosing a clustering key are critical to remember. Even veterans can use some re-enforcement of the fundamentals from time to time. I thought the article was great!
+1 to that. It is a very good article and as the stairway progresses will for sure leave the audience with a sound understanding of the working of the indexes.
We have used the non clustered indexes on a heap approach for tables that are not joined with other tables and where range queries are infrequently made.
Transaction tables forming part of entity-relationships though, as a general rule of thumb, are clustered.
August 3, 2011 at 6:51 am
I thought the article had good information, but perhaps more attention could have been paid to the characteristics of a good key, bringing up the whole surrogate key idea--unless that's another step on the stairway?
August 3, 2011 at 10:33 am
I liked the article, but I think the "which is better" section is a little misleading. There are lots of good reasons to prefer tables with clustered indexes that were just out of scope for the article. Range data access, relationships, space management, etc.
August 8, 2011 at 4:00 pm
Steve.Cornelius (8/3/2011)
I see very little of value in this article. The readers are ever so slightly better informed after reading it, but have acquired no useful information. In fact if your conclusions, or lack thereof, are to be believed no decisions should be altered based on the entire topic. As such wouldn't it have been better not to publish it and thus save us all the time spent reading it? This strikes me as the sort of irrelevant waffle published by academics that gives academia a bad name.Before your next article please try to establish that the topic is worth reading about before writing about it.
Steve, I don;t understand why your first post is so negative. I have been following this series of articles and have found it most interesting on how the underlying disk structure funtions. This one added heaps to my knowledge (bad pun intended). Are you setting yourself up as "one to watch" due to extreme negativity and nastyness?
August 9, 2011 at 2:29 am
Are you setting yourself up as "one to watch" due to extreme negativity and nastyness?
Please don't assign such petty motivations to me. I'm not one of these shallow idiots who thinks that attention=success. Now I've wasted enough time on this already.
August 9, 2011 at 6:33 am
Steve.Cornelius (8/9/2011)
Are you setting yourself up as "one to watch" due to extreme negativity and nastyness?
Please don't assign such petty motivations to me. I'm not one of these shallow idiots who thinks that attention=success. Now I've wasted enough time on this already.
Wow Steve, not much ambiguity there, and not much help either I might add. I for one hope you feel the same way about the entire site and you'll move on to grace others with your presence and wisdom elsewhere.
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato
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