X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/0f3010ab0d076d01b31019d902bfc94ca1e310d3..cc2750670f1cb2fafde3e7d1a340f6674dab1749:/doc/SetbitCommand.html diff --git a/doc/SetbitCommand.html b/doc/SetbitCommand.html new file mode 100644 index 00000000..bcec9e22 --- /dev/null +++ b/doc/SetbitCommand.html @@ -0,0 +1,45 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SetbitCommand: Contents</b><br> <a href="#SETBIT _key_ _offset_ _value_ (Redis >">SETBIT _key_ _offset_ _value_ (Redis ></a><br> <a href="#Return value">Return value</a> + </div> + + <h1 class="wikiname">SetbitCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + +<h1><a name="SETBIT _key_ _offset_ _value_ (Redis >">SETBIT _key_ _offset_ _value_ (Redis ></a></h1> 2.1.8) = +<i>Time complexity: O(1)</i><blockquote>Sets or clears the bit at <i>offset</i> in the string value stored at <i>key</i>.</blockquote> +The bit is either set or cleared depending on <i>value</i>, which can be either 0 or 1. When <i>key</i> does not exist, a new string value is created. The string is grown to make sure it can hold a bit at <i>offset</i>. The <i>offset</i> argument is required to be greater than or equal to 0, and is limited to 2<sup>32-1 (which limits bitmaps to 512MB). +When the string at <i>key</i> is grown, added bits are set to 0.<br/><br/><b>Warning</b>: When setting the last possible bit (<i>offset</i> equal to 2</sup>32-1) and the string value stored at <i>key</i> does not yet hold a string value, or holds a small string value, Redis needs to allocate all intermediate memory which can block the server for some time. +On a 2010 Macbook Pro, setting bit number 2<sup>32-1 (512MB allocation) takes ~300ms, +setting bit number 2</sup>30-1 (128MB allocation) takes ~80ms, +setting bit number 2<sup>28-1 (32MB allocation) takes ~30ms and +setting bit number 2</sup>26-1 (8MB allocation) takes ~8ms. +Note that once this first allocation is done, subsequent calls to SETBIT for the same <i>key</i> will not have the allocation overhead.<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically: the original bit value stored at <i>offset</i>. + </div> + + </div> + </div> + </body> +</html> +