• 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

    • I don't think RTSS can show the real framerate. In fact, this is the first time I have ever heard about anything showing it.
    • Yeah, Deck's overlay has CPU temps. Maybe they don't want to rely on external dlls to provide CPU temperature graphs on all machines? From my experience with Rivatuner it can be annoying to select the correct CPU temperature sensor.
    • Why would I be praising Microsoft? You do realize I'm well aware the Gamebar is a stinking pile of crap and has been for years, right? Or are you one of those "if you don't critique something at every turn you area clearly a fanboy" people? Yes, MangoHUD is built into SteamOS's Big Picture mode, and up until a few weeks ago, SteamOS was exclusive to... the Steam Deck... for 3 years. Yet you were talking about it as if you didn't need to set it up yourself, like it was built into other distributions, which it wasn't. So if we ignore the real/fake framerate feature, it's really not much different than me setting up my Rivatuner/HWInfo overlay, is it? Valve had the option of building MangoHUD into Steam, like they are doing it now, for 3 years. So let's not pretend Windows hasn't had a basic way to display your framerate built in, keeping well aware how crap it actually is. And I'm not even counting your GPU driver company, because Nvidia, AMD and Intel have their own (somehow even worse than GameBar) overlays. And of course they won't tell you fake/real framerate, why would Nvidia nor AMD want to tell you? That is absolutely a +1 on Valve.
    • As much as I like the push towards Wayland (is Gnome still bickering about window decorations and "you are doing it wrong"ing rest of the industry?) but as an admin, the fact that the FreeRDP (because VNC is dead) implementation is not functional yet is really annoying, as that is what RHEL10, and Debian13, will be stuck with for the next 3-8 years.
    • qBittorrent 5.1.1 by Razvan Serea The qBittorrent project aims to provide a Free Software alternative to µtorrent. qBittorrent is an advanced and multi-platform BitTorrent client with a nice user interface as well as a Web UI for remote control and an integrated search engine. qBittorrent aims to meet the needs of most users while using as little CPU and memory as possible. qBittorrent is a truly Open Source project, and as such, anyone can and should contribute to it. qBittorrent features: Polished µTorrent-like User Interface Well-integrated and extensible Search Engine Simultaneous search in most famous BitTorrent search sites Per-category-specific search requests (e.g. Books, Music, Movies) All Bittorrent extensions DHT, Peer Exchange, Full encryption, Magnet/BitComet URIs, ... Remote control through a Web user interface Nearly identical to the regular UI, all in Ajax Advanced control over trackers, peers and torrents Torrents queueing and prioritizing Torrent content selection and prioritizing UPnP / NAT-PMP port forwarding support Available in ~25 languages (Unicode support) Torrent creation tool Advanced RSS support with download filters (inc. regex) Bandwidth scheduler IP Filtering (eMule and PeerGuardian compatible) IPv6 compliant Available on most platforms: Linux, Mac OS X, Windows, OS/2, FreeBSD qBittorrent 5.1.1 changelog: BUGFIX: Don't interpret wildcard pattern as filepath globbing (glassez) BUGFIX: Fix appearance of search history length spinbox (glassez) BUGFIX: Remove dubious seeding time max value (glassez) BUGFIX: Fix ratio handling (glassez) BUGFIX: Fix compilation with Qt 6.6.0 (glassez) WEBUI: Make General tab text selectable by default (dezza) WEBUI: Add versioning to local preferences (Chocobo1) WEBUI: Make multi-rename search & replace fields use a monospace font (Atk) WEBUI: Fix wrong replacement sequence in IPv6 string (Chocobo1) WEBUI: Fix memory leak (bolshoytoster) WEBUI: Fix path autofill in set location and new category (tehcneko) RSS: Mark matched article as "read" if it refers to a duplicate torrent (glassez) WINDOWS: Update command line help message (KanishkaHalder1771) WINDOWS: NSIS: Don't require agreement on the license page (Chocobo1) LINUX: Fix preview not opening on Wayland (Isak05) LINUX: Add fallback for random number generator (Chocobo1) Download: qBittorrent 5.1.1 | Portable | ~40.0 MB (Open Source) Download: qBittorrent 64-bit installer (qt6) | 41.7 MB Links: qBittorrent Home page | Screenshot Get alerted to all of our Software updates on Twitter at @NeowinSoftware
  • Recent Achievements

    • Week One Done
      urbanmopdubai1 earned a badge
      Week One Done
    • One Month Later
      Jim Dugan earned a badge
      One Month Later
    • First Post
      Johnny Mrkvička earned a badge
      First Post
    • Week One Done
      viraltui earned a badge
      Week One Done
    • One Month Later
      serfegyed earned a badge
      One Month Later
  • Popular Contributors

    1. 1
      +primortal
      654
    2. 2
      Michael Scrip
      227
    3. 3
      ATLien_0
      218
    4. 4
      Steven P.
      150
    5. 5
      Xenon
      145
  • Tell a friend

    Love Neowin? Tell a friend!