Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p><em><strong>Note:</em></strong> <em>I thought I could come up with a faster solution with a single regex, but I couldn't. Below is my failed method (you can learn from failure), and the results of a performance test, and my conclusion.</em></p> <p>Efficiency can be measured many ways. If you wanted to reduce the number of functions called, then you could use a single regex and a function to handle the replacement.</p> <pre><code>([A-Z])|(\s)|([^a-z\d]) </code></pre> <p><strong><a href="http://rey.gimenez.biz/s/3ifilj" rel="nofollow">REY</a></strong></p> <p>The first group will have <code>toLowerCase()</code> applied, the second will be replaced with a <code>-</code> and the third will return nothing. I originally used <code>+</code> quantifier for groups 1 and 3, but given the expected nature of the text, removing it result in faster execution. <em>(thanks acheong87)</em></p> <pre><code>'Well Done!'.replace(/([A-Z])|(\s)|([^a-z\d])/g, function (match, $0, $1) { if ($0) return String.fromCharCode($0.charCodeAt(0) + 32); else if ($1) return '-'; return ''; }); </code></pre> <p><strong><a href="http://jsfiddle.net/TgFgT/9/" rel="nofollow">jsFiddle</a></strong></p> <p><strong>Performance</strong></p> <p>My method was the worst performing:</p> <pre><code>Acheong87 fastest Original 16% slower Mine 53% slower </code></pre> <p><strong><a href="http://jsperf.com/18335656" rel="nofollow">jsPerf</a></strong></p> <p><strong>Conclusion</strong></p> <p>Your method <em>is the most efficient</em> in terms of code development time, and the performance penalty versus acheong87's method is offset by code maintainability, readability, and complexity reduction. I would use your version unless speed was of the utmost importance.</p> <p>The more optional matches I added to the regular expression, the greater the performance penalty. I can't think of any advantages to my method except for the function reduction, but that is offset by the <code>if</code> statements and increase in complexity.</p>
    singulars
    1. This table or related slice is empty.
    1. POIs there a cleaner way to remove non-alphanumeric chars and replace spaces?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USDaniel Gimenez
    1. USDaniel Gimenez
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POIs there a cleaner way to remove non-alphanumeric chars and replace spaces?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. CONice; thanks for the benchmarks; I didn't know about this site. I wonder what the difference would be if you reversed the order of the alternation atoms (since spaces are the rarest, uppercase letters the second rarest, and lowercase letters the most common). Also, one of the reasons the above may be inefficient is that it requires backtracking. I see in _spirit_ you're trying to minimize _replacements_, but the `+` forces a "failed match" to occur before the next alternation atom is tested, whereas without the `+`, replacements are immediate. I'm not sure what the underlying code looks like
      singulars
      1. PO
      1. USAndrew Cheong
    2. COin the JS engine, but I wonder if replacement time is more related to the number of characters rather than the number of invocations. I just edited your test to give these modifications a shot; hm, the performance benefits weren't as large as I thought they'd be. Indeed, a good example to learn from. (Now editing my answer to also include regex whitespace characters, _i.e._ `[ \f\n\r\t\v]`.
      singulars
      1. PO
      1. USAndrew Cheong
    3. CO@acheong87, you're right in both regards. The nature of the sample text and practical usage makes `+` inefficient in terms of performance. Changing the order will also help if we expect capital letters to be more frequent.
      singulars
      1. PO
      1. USDaniel Gimenez
 

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