Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>I had a bit of time over lunch:</p> <pre><code>public static void main(String[] args) { final int[] a = new int[250000000]; long t; for (int j = 0; j &lt; 10; j++) { t = System.currentTimeMillis(); for (int i = 0, n = a.length; i &lt; n; i++) { int x = a[i]; } System.out.println("n = a.length: " + (System.currentTimeMillis() - t)); t = System.currentTimeMillis(); for (int i = 0; i &lt; a.length; i++) { int x = a[i]; } System.out.println("i &lt; a.length: " + (System.currentTimeMillis() - t)); } } </code></pre> <p>The results:</p> <pre><code>n = a.length: 672 i &lt; a.length: 516 n = a.length: 640 i &lt; a.length: 516 n = a.length: 656 i &lt; a.length: 516 n = a.length: 656 i &lt; a.length: 516 n = a.length: 640 i &lt; a.length: 532 n = a.length: 640 i &lt; a.length: 531 n = a.length: 641 i &lt; a.length: 516 n = a.length: 656 i &lt; a.length: 531 n = a.length: 656 i &lt; a.length: 516 n = a.length: 656 i &lt; a.length: 516 </code></pre> <p>Notes:</p> <ol> <li>If you reverse the tests, then <code>n = a.length</code> shows as being faster than <code>i &lt; a.length</code> by about half, probably due to garbage collection(?).</li> <li>I couldn't make <code>250000000</code> much larger because I got <code>OutOfMemoryError</code> at <code>270000000</code>.</li> </ol> <p>The point is, and it is the one everyone else has been making, you have to run Java out of memory and you still don't see a significant difference in speed between the two alternatives. Spend your development time on things that actually matter.</p>
    singulars
    1. This table or related slice is empty.
    1. POWhat is the Cost of Calling array.length
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USGrant Wagner
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COtry java -Xmx512M to make the heap bigger...
      singulars
      1. PO
      1. USwbkang
    2. COThis matters in C/C++.
      singulars
      1. PO
      1. USBrian Liang
    3. CO@wbkang: Identifying that my default heap size was insufficient for a very large array wasn't really the point of the exercise.
      singulars
      1. PO
      1. USGrant Wagner
 

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