• 0

c# Short URL from GUID


Question

Hello gang,

 

I am working on a new project for a site and I would like to implement short urls.  Historically I have used GUIDs as table ids so that replication is not an issue.  So, now I'm looking at creating a short url for these values, the thing is a shortened guid is not that short (vs a shortened Int) Before getting too far down a path, I thought I'd ask if anyone had any thoughts.

 

Thanks

Link to comment
https://www.neowin.net/forum/topic/1203663-c-short-url-from-guid/
Share on other sites

16 answers to this question

Recommended Posts

  • 0

Just generate strings of whatever size you consider to be short, made up of numbers, uppercase letters and lowercase letters, and associated them with your ID field.

 

[short_url_assoc_table]

table_id : GUID

short_url : string

  • 0
  On 06/03/2014 at 20:00, firey said:

What is it you are trying to do?

Like you have something say:

guasd3 = www.google.ca

-3idjqis = www.neowin.net

or?  

I guess I don't understand what you are trying to do exactly.

 

 

I need to use GUIDs as the table ident fields for the issue of replication.  If I use numeric values for the identity, which is easy to convert to a short URL by using Base64 (quite a number of examples around the net for doing this)  however if I use numeric I'm going to have collisions when multiple machines are making new records.  When I have looked at making a short url from a guid, the value is shorter than the GUID, but still longer than the average short GUID.

 

  On 06/03/2014 at 20:32, virtorio said:

Just generate strings of whatever size you consider to be short, made up of numbers, uppercase letters and lowercase letters, and associated them with your ID field.

 

[short_url_assoc_table]

table_id : GUID

short_url : string

 

Interesting idea, but this could be an issue with replication.  I am also concerned about multiple identity fields (waste of time, space, etc)   Thanks though

  • 0
  On 06/03/2014 at 21:16, James Rose said:

 

 

Interesting idea, but this could be an issue with replication.  I am also concerned about multiple identity fields (waste of time, space, etc)   Thanks though

 

What exactly is being replicated?

 

 

  On 06/03/2014 at 21:16, James Rose said:

I need to use GUIDs as the table ident fields for the issue of replication.  If I use numeric values for the identity, which is easy to convert to a short URL by using Base64 (quite a number of examples around the net for doing this)  however if I use numeric I'm going to have collisions when multiple machines are making new records.  When I have looked at making a short url from a guid, the value is shorter than the GUID, but still longer than the average short GUID.

What am I missing here? This shouldn't be an issue with a relational database. You don't tell your database what the ID of a row is, you let the database decide when it inserts the row(s).

  • 0

Im not sure where replication is happening.  Also why do you have to use guids for the identity, why not just use an incrementing number, and hash it's value or something to get the url you want to use?  Also, the database should be able to handle the ID itself.. and there should never be an issue of too many inserts causing problems.

  • Like 1
  • 0

Okay gang,

 

Replication of tables between multiple servers cannot use numeric values as, for example in SQL Server the Identity value is incrimented by 1 (and yes, you can change this value, but it wouldn't help when the app needs to scale)  Imagine two servers, each one adding new values to a table; "Customers" One each server they would both get identity #1 for the first record, when the two servers attempt to merge (ever hour, every minute, whenever) there would be a collision since there would be two records with the same identity value.  Using GUIDs for the key field avoids this issue as it is, almost, impossible to have the same guid twice.

 

 

Thanks Asik, however the "guidAsString" variable is still too long to be a short url.

  • 0

Looks like I found the answer.

                //Guid guid = Guid.NewGuid();
                string sGUID = "a33d4a21-7d95-41f7-859e-bf02b2fda650"
                string hashCode = String.Format("{0:X}", sGUID.GetHashCode());
                Console.WriteLine(hashCode);

This makes a nice small url, can anyone think of why this should not be used?

  • 0

^you shouldn't use it for the reasons listed here (about uniqueness guarantees and differences between versions): http://stackoverflow.com/questions/7458139/net-is-type-gethashcode-guaranteed-to-be-unique

 

Hash the GUID using SHA1 and truncate it or something like that. That's probably the best you are going to do. (perhaps you will have to truncate it to much, forcing a too high of probability for collision -- you should check the probability).

 

EDIT: Oh also, if you encode the result of hashing in a higher base, you reduce the amount of information loss during truncation.

  • 0
  On 06/03/2014 at 22:13, snaphat (Myles Landwehr) said:

^you shouldn't use it for the reasons listed here (about uniqueness guarantees and differences between versions): http://stackoverflow.com/questions/7458139/net-is-type-gethashcode-guaranteed-to-be-unique

 

Hash the GUID using SHA1 and truncate it or something like that. That's probably the best you are going to do. (perhaps you will have to truncate it to much, forcing a too high of probability for collision -- you should check the probability).

 

EDIT: Oh also, if you encode the result of hashing in a higher base, you reduce the amount of information loss during truncation.

 

EDIT:  Maybe what the article is saying, and what you are trying to tell me is that two different GUIDs could return the same hex?

 

 

 

Pardon me if I appear dense; I just read that article and ran some test against the same guid value for 1 billion iterations and it always comes up with the same hex.  I understand that 1 billion isn't necessarily that large a number...  what I am asking is shouldn't the hex value for a specific string always return the same hex value. 

 

Quote: "does not guarantee unique return values for different objects."  Since the app will pull the guid from the db, and then issue a hex on demand wouldn't that value always be the same?

 

Thanks for your input

  • 0
  On 06/03/2014 at 22:25, James Rose said:

Pardon me if I appear dense; I just read that article and ran some test against the same guid value for 1 billion iterations and it always comes up with the same hex.  I understand that 1 billion isn't necessarily that large a number...  what I am asking is shouldn't the hex value for a specific string always return the same hex value. 

 

Quote: "does not guarantee unique return values for different objects."  Since the app will pull the guid from the db, and then issue a hex on demand wouldn't that value always be the same?

 

Thanks for your input

 

It's the same each time because you are using the same version of the .net runtime on the same object for each run so it's producing the same hash. What they are saying is really two things: (1) if you switch versions of the .net runtime (e.g. 3.5 to 4), the returned result can be different for the same object, and (2) and within the same version of the runtime (e.g. 4) there can be collisions in hashes between different objects. There are no uniqueness guarantees.

 

So for example GUID_A.getHashCode() can return different results if you switch .net runtimes. And GUID_B.getHashCode() and GUID_C.getHashCode() could return the same result in the same runtime.

  • 0
  On 06/03/2014 at 22:31, snaphat (Myles Landwehr) said:

So for example GUID_A.getHashCode() can return different results if you switch .net runtimes. And GUID_B.getHashCode() and GUID_C.getHashCode() could return the same result in the same runtime.

 

yea, this is the answer I finally got to (see my edit above).  I was having a very hard time getting to the idea that a 30+ char piece of data could reliably be set to a shorter value.

  • 0
  On 06/03/2014 at 22:39, James Rose said:

yea, this is the answer I finally got to (see my edit above).  I was having a very hard time getting to the idea that a 30+ char piece of data could reliably be set to a shorter value.

Well in any case, you should re-encode whatever you do use to a higher number base that is still valid as url characters. For example, as I was saying before if you do the following you can store more information of your hash in less characters. 

String result=re_encode_as_base_X(SHA1_hash(GUID), N) //base 16 --> base N

I think at the end of the day, you will have to truncate though regardless of what you do. 

  • 0

It turns out I may be suffering from "doing this too long" desease.  Someone was kind enough to send a private message to me that the issue of replication on numeric  idenities may no longer be the issue it used to be.

 

I'm reading this article now:  http://technet.microsoft.com/en-us/library/ms146907%28v=sql.105%29.aspx

  • Like 1
  • 0
  On 06/03/2014 at 22:01, James Rose said:

Thanks Asik, however the "guidAsString" variable is still too long to be a short url.

I was suggesting taking the BigInteger and passing it through whatever method you mentionned that converted numerical values into short URLs, not taking it as a string directly. Anyway, looks like you found your answer.

This topic is now closed to further replies.
  • Posts

    • Taras Buria, do you think you could write more about Windows Vista? It is always such a pleasure — quite a pleasure — to see it mentioned in the title of a news article. What about an editorial?
    • Alienware 34 240Hz QD-OLED Monitor: A premium ultrawide for serious gamers - save $100! by Paul Hill Are you a serious gamer looking to save money on a monitor upgrade? If so, check out this deal on the Alienware 34 240Hz QD-OLED Gaming Monitor (AW3425DW), which is discounted by 13% from $799.99 to just $699.99. This ultrawide monitor features a 3,440 x 1,440 pixel display and the screen is curved for added immersion. Two features that will stand out to competitive gamers are the 240Hz refresh rate and 0.03ms GtG response time which will minimize any lagging from input to display, making you a more lethal player. Why QD-OLED matters for gamers and creators This Alienware uses QD-OLED (Quantum Dot Organic Light Emitting Diode) technology which combines OLED’s self-emitting LEDs with the color-enhancing capabilities of quantum dots. This results in higher brightness, a wider color gamut, deeper blacks, and wide viewing angles. With the 1800R curve built into this display, whatever you’re immersed in will wrap around, making your games more absorbing, potentially reducing other distractions. There is also VESA DisplayHDR TrueBlack 400 certification and 1,000 nits peak HDR brightness on this display. Gamers using this monitor will be able to get the best quality picture from this monitor to improve the experience and their competitiveness. It’s also good for creators who want to edit images and videos as they will see the content they're editing in the best ways possible, so they can be totally sure it’s ready for publication. Design, connectivity, and user experience The Alienware 34 uses an updated Interstellar Indigo design which is more compact and uses a flat stand. This frees up desk space compared to older Alienware designs and still allows for height, tilt, and swivel adjustments and VESA mount compatibility. Regarding ports, this monitor features 2x HDMI 2.1, 1x DisplayPort 1.4, 1x USB 5Gbps Type-B upstream, 1x USB 5Gbps Type-A downstream, 1x USB-C 5Gbps downstream with 15W charging. The USB-C port is for data and charging, not video input and the lack of KVM switch could be a drawback for some. If you decide to pick up this monitor, according to PCWorld, it does not include in-built speakers so you will need to connect your own. This is not a big issue because gamers looking for a premium playing experience will not want to rely on subpar in-built speakers anyway. Is the AW3425DW the right fit for you? Given its curved display, quality QD-LED display technology, and its fast response time, this monitor is a great pick for serious gamers looking for top-tier performance and immersion. Content creators who value color accuracy will also do well in picking up this Alienware monitor. Alienware 34: $699.99 (Amazon US) / MSRP $799.99 This Amazon deal is US-specific and not available in other regions unless specified. If you don't like it or want to look at more options, check out the Amazon US deals page here. Get Prime (SNAP), Prime Video, Audible Plus or Kindle / Music Unlimited. Free for 30 days. As an Amazon Associate, we earn from qualifying purchases.
  • Recent Achievements

    • Rising Star
      Phillip0web went up a rank
      Rising Star
    • One Month Later
      Epaminombas earned a badge
      One Month Later
    • One Year In
      Bert Fershner earned a badge
      One Year In
    • Reacting Well
      ChrisOdinUK earned a badge
      Reacting Well
    • One Year In
      Steviant earned a badge
      One Year In
  • Popular Contributors

    1. 1
      +primortal
      545
    2. 2
      ATLien_0
      205
    3. 3
      +FloatingFatMan
      170
    4. 4
      Michael Scrip
      150
    5. 5
      Som
      131
  • Tell a friend

    Love Neowin? Tell a friend!