Frank, that puts the logic at the rdbms engine and no longer in your app, in-front of your data.
In reality, you get data all over the place but this bunch will be close. Pound script this a few times and you will see the leading values are what changes an not the last 4-5-6 characters. CREATE TABLE GUID_Example ( SeqCol uniqueidentifier DEFAULT NewSequentialID() ,IDCol uniqueidentifier DEFAULT NEWID(),) ----Inserting five default values in table INSERT INTO GUID_Example DEFAULT VALUES INSERT INTO GUID_Example DEFAULT VALUES INSERT INTO GUID_Example DEFAULT VALUES INSERT INTO GUID_Example DEFAULT VALUES --------------------------------------------------------- SELECT * FROM GUID_Example ----Clean up database DROP TABLE GUID_Example I got this as output : SeqCol IDCol 1E54CB01-A7BD-E711-9C54-D481D71992B4 120C2AD7-ECF1-487F-BE56-0FD36A78237F 1F54CB01-A7BD-E711-9C54-D481D71992B4 E6F5D7B5-61F8-4FD3-988B-F0949A029E29 2054CB01-A7BD-E711-9C54-D481D71992B4 B5C05851-FBA5-4DD7-864A-133EE1BC6C68 2154CB01-A7BD-E711-9C54-D481D71992B4 638865DA-F2E4-4101-9534-E3DB83A0008E When the performance goes to insert all over the index pages where there is a lot of available room you may not have a performance hit at all. On the flip side using the newsequentialID it may make a compound insert into a page that was starting to get tight and now is tight. Please remember folks that Fkey index is also a component in the insert event as well. The more indexes you maintain that you really don't need, do get in your way on any platform. On Mon, Oct 30, 2017 at 1:23 PM, Frank Cazabon <[email protected]> wrote: > I believe NewSequentialID() in SQL Server (or the UuidCreateSequential API > call) avoids the paging problem behind Guids. > > Frank. > > Frank Cazabon > > > On 30/10/2017 02:17 PM, Stephen Russell wrote: > >> Good URLs you presented. >> >> To me from a performance POV the INSERT of the GUID is the only downside >> with respect to the index. It has to identify the page and add itself to >> there. If need be it will tear the page and generate two pages with >> access >> holes to accept new index-data going forward. Next. you look at the type >> of data you are presenting via a velocity of inserts. Are your inserts >> per >> min to a table > 10,000? If so the GUID may be the wrong thing. Think of >> eBay in the closing seconds of an auction, or your stock trader in >> changes in the market generating A LOT of transactions. These situations >> are where next int is best because it always going to the last page of the >> index. >> >> If you are not in that type of data environment you can do either with no >> problem. >> >> M$ loves using GUID in their internal systems like CRM or SharePoint. It >> is Massive GUID driven in all of the tables. >> >> >> >> >> >> >> >> On Mon, Oct 30, 2017 at 12:42 PM, < >> [email protected]> wrote: >> >> On 2017-10-30 11:09, Stephen Russell wrote: >>> >>> Less efficient indexes? Are you talking about space in a db compared to >>>> an >>>> int for a pointer or are you saying that the time to isolate the data on >>>> that row because of the data type of the pointer? The flip side is data >>>> insertion. >>>> >>>> Can you tell us why you use less efficient? >>>> >>>> >>>> Not sure of your wording, if you meant exactly that or not, so let me >>> try >>> to respond: >>> >>> I like the guid v(40) indexes because if ever I needed to combine data, >>> I'm not running into duplicate keys. Plus, I like defining the key ahead >>> of time and having complete control so I can work with >>> parent/child/grandchild datasets easier (than if I had to contend with >>> auto-inc keys). The negative of this approach as I understood it is that >>> the since the index is 4x larger in size than a 4-byte integer key, it >>> would not be as efficient in memory, and the index tree needs reindexing >>> more often so as to be balanced. >>> >>> Plenty of good article on the interweb discussing both: >>> http://www.ovaistariq.net/733/understanding-btree-indexes-an >>> d-how-they-impact-performance/#.WfdQDHYpCJA >>> https://blog.codinghorror.com/primary-keys-ids-versus-guids/ >>> http://web.archive.org/web/20150511162734/http://databases. >>> aspfaq.com/database/what-should-i-choose-for-my-primary-key.html >>> >>> I think I'll stick with app-generated GUIDs though for the portability >>> and >>> no-collision benefit if I merged/move data. I also want to do >>> replication >>> where their database is stored locally but then replicates to a master >>> database outside their office. >>> [excessive quoting removed by server] _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://mail.leafe.com/mailman/listinfo/profox OT-free version of this list: http://mail.leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/CAJidMY+tOKKLmgedjrFQfOFZwHPq=nvkdtwvfdo98ae0ouk...@mail.gmail.com ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
