Databases
StackOverflow2013
Postsdbo
POPros and cons of using md5 hash of URI as the primary key in a database
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POPros and cons of using md5 hash of URI as the primary key in a database
    primarykey
    data
    text
    <p>I'm building a database that will store information on a range of objects (such as scientific papers, specimens, DNA sequences, etc.) that all have a presence online and can be identified by a URL, or an identifier such as a <a href="http://www.doi.org/" rel="noreferrer" title="DOI">DOI</a>. Using these GUIDs as the primary key for the object seems a reasonable idea, and I've followed <a href="http://delicious.com/" rel="noreferrer" title="delicious">delicious</a> and <a href="http://www.connotea.org" rel="noreferrer" title="Connotea">Connotea</a> in using the md5 hash of the GUID. You'll see the md5 hash in your browser status bar if you mouse over the edit or delete buttons in a delicious or Connotea book mark. For example, the bookmark for <a href="http://stackoverflow/" rel="noreferrer">http://stackoverflow/</a> is </p> <pre><code>http://delicious.com/url/e4a42d992025b928a586b8bdc36ad38d </code></pre> <p>where e4a42d992025b928a586b8bdc36ad38d ais the md5 hash of <a href="http://stackoverflow/" rel="noreferrer">http://stackoverflow/</a>.</p> <p>Does anybody have views on the pros and cons of this approach?</p> <p>For me an advantage of this approach (as opposed to using an auto incrementing primary key generated by the database itself) is that I have to do a lot of links between objects, and by using md5 hashes I can store these links externally in a file (say, as the result of data mining/scraping), then import them in bulk into the database. In the same way, if the database has to be rebuilt from scratch, the URLs to the objects won't change because they use the md5 hash.</p> <p>I'd welcome any thoughts on whether this sounds sensible, or whether there other (better?) ways of doing this.</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USrdmpage
    plurals
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POPros and cons of using md5 hash of URI as the primary key in a database
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POPros and cons of using md5 hash of URI as the primary key in a database
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POPros and cons of using md5 hash of URI as the primary key in a database
      1. USGuido García
      1. VTFavorite
    1. CODid you end up using an md5 as your primary key? How did it go?
      singulars
      1. POPros and cons of using md5 hash of URI as the primary key in a database
      1. USPaul Tarjan
    2. COAny of non-unique values can be used for indexing, but never for PK.
      singulars
      1. POPros and cons of using md5 hash of URI as the primary key in a database
      1. USEonil
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload