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  19 <b>KeysCommand: Contents
</b><br>  <a href=
"#KEYS _pattern_">KEYS _pattern_
</a><br>    <a href=
"#Return value">Return value
</a> 
  22                 <h1 class=
"wikiname">KeysCommand
</h1> 
  29                     #sidebar 
<a href=
"GenericCommandsSidebar.html">GenericCommandsSidebar
</a><h1><a name=
"KEYS _pattern_">KEYS _pattern_
</a></h1> 
  30 <i>Time complexity: O(n) (with n being the number of keys in the DB, and assuming keys and pattern of limited length)
</i><blockquote>Returns all the keys matching the glob-style 
<i>pattern
</i> asspace separated strings. For example if you have in thedatabase the keys 
"foo
" and 
"foobar
" the command 
"KEYS foo
<code name=
"code" class=
"python">*
</code>"will return 
"foo foobar
".
</blockquote> 
  31 <blockquote>Note that while the time complexity for this operation is O(n)the constant times are pretty low. For example Redis runningon an entry level laptop can scan a 
1 million keys databasein 
40 milliseconds. 
<b>Still it's better to consider this one of
 
  32 <blockquote>the slow commands that may ruin the DB performance if not usedwith care*.
</blockquote> 
  33 <blockquote>In other words this command is intended only for debugging and *special* operations like  creating a script to change the DB schema. Don't use it in your normal code. Use Redis 
<a href=
"Sets.html">Sets
</a> in order to group together a subset of objects.
</blockquote> 
  34 Glob style patterns examples:
 
  35 <blockquote>* h?llo will match hello hallo hhllo* h*llo will match hllo heeeello* h
<code name=
"code" class=
"python">[
</code>ae
<code name=
"code" class=
"python">]
</code>llo will match hello and hallo, but not hillo
</blockquote>Use \ to escape special chars if you want to match them verbatim.
<h2><a name=
"Return value">Return value
</a></h2><a href=
"ReplyTypes.html">Bulk reply
</a>, specifically a string in the form of space separated list of keys. Note that most client libraries will return an Array of keys and not a single string with space separated keys (that is, split by 
" " is performed in the client library usually).
</b></blockquote>