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session_unique_id.html
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session_unique_id.html
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<title>session_unique_id: common_schema documentation</title>
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<h1>common_schema</h1> <strong>2.2</strong> documentation
<div class="subtitle">DBA's framework for MySQL</div>
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<h2><a href="session_unique_id.html">session_unique_id</a></h2>
<h3>NAME</h3>
session_unique_id(): Return a unique unsigned integer for this session
<h3>TYPE</h3>
Function
<h3>DESCRIPTION</h3>
<p>
This function returns unique values per session. That is, any two calls to this function from within the same session,
result with different, unique values.
</p>
<p>
The function utilizes the fact that a session is managed serially (it it generally unsafe and undesired to issue concurrent
queries on same connection). Therefore, it is known that any two calls on this function are essentially serialized within
the session
</p>
<p>
Current implementation of this function is to return incrementing unsigned integer values. However, the user should not
rely on this behavior, and should not assume consecutive results on consecutive calls.
</p>
<h3>SYNOPSIS</h3>
<p>
<blockquote><pre>session_unique_id()
RETURNS INT UNSIGNED</pre></blockquote>
</p>
<p>
Output:
<ul>
<li>A unique value within current session.
</ul>
</p>
<h3>EXAMPLES</h3>
<p>
Get unique values:
</p>
<blockquote><pre>mysql> SELECT session_unique_id(), session_unique_id();
+---------------------+---------------------+
| session_unique_id() | session_unique_id() |
+---------------------+---------------------+
| 1 | 2 |
+---------------------+---------------------+
1 row in set (0.02 sec)
mysql> SELECT session_unique_id();
+---------------------+
| session_unique_id() |
+---------------------+
| 3 |
+---------------------+
<h3>ENVIRONMENT</h3>
MySQL 5.1 or newer
<h3>AUTHOR</h3>
Shlomi Noach
<br/>
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