157 lines
8.3 KiB
HTML
157 lines
8.3 KiB
HTML
|
<?xml version="1.0" encoding="utf-8"?>
|
||
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
|
||
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
|
|
<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-us">
|
||
|
|
<head>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||
|
|
<meta name="dc.language" scheme="rfc1766" content="en-us" />
|
||
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
||
|
|
<!-- US Government Users Restricted Rights -->
|
||
|
|
<!-- Use, duplication or disclosure restricted by -->
|
||
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
||
|
|
<meta name="dc.date" scheme="iso8601" content="2005-09-19" />
|
||
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
|
||
|
|
<meta name="security" content="public" />
|
||
|
|
<meta name="Robots" content="index,follow"/>
|
||
|
|
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
|
||
|
|
<meta name="keywords" content="SET CURRENT DEGREE statement, SET CURRENT DEGREE,
|
||
|
|
SQL statements" />
|
||
|
|
<title>SET CURRENT DEGREE</title>
|
||
|
|
<link rel="stylesheet" type="text/css" href="ibmidwb.css" />
|
||
|
|
<link rel="stylesheet" type="text/css" href="ic.css" />
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<a id="Top_Of_Page" name="Top_Of_Page"></a><!-- Java sync-link -->
|
||
|
|
<script language = "Javascript" src = "../rzahg/synch.js" type="text/javascript"></script>
|
||
|
|
|
||
|
|
|
||
|
|
<a name="setdegree"></a>
|
||
|
|
<h2 id="setdegree"><a href="rbafzmst02.htm#ToC_1290">SET CURRENT DEGREE</a></h2><a id="idx3128" name="idx3128"></a><a id="idx3129" name="idx3129"></a>
|
||
|
|
<p>The SET CURRENT DEGREE statement assigns a value to the CURRENT DEGREE
|
||
|
|
special register.</p>
|
||
|
|
<a name="wq1743"></a>
|
||
|
|
<h3 id="wq1743"><a href="rbafzmst02.htm#ToC_1291">Invocation</a></h3>
|
||
|
|
<p>This statement can be embedded in an application program or
|
||
|
|
issued interactively. It is an executable statement that can be dynamically
|
||
|
|
prepared. It must not be specified in REXX.</p>
|
||
|
|
<a name="wq1744"></a>
|
||
|
|
<h3 id="wq1744"><a href="rbafzmst02.htm#ToC_1292">Authorization</a></h3>
|
||
|
|
<p>The privileges held by the authorization ID of the statement must include
|
||
|
|
the system authority of *JOBCTL.</p>
|
||
|
|
<a name="wq1745"></a>
|
||
|
|
<h3 id="wq1745"><a href="rbafzmst02.htm#ToC_1293">Syntax</a></h3>
|
||
|
|
<a href="rbafzsetdegree.htm#synsetdegree"><img src="c.gif" alt="Click to skip syntax diagram" /></a>
|
||
|
|
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn380.htm"
|
||
|
|
border="0" /></span><a href="#skipsyn-379"><img src="c.gif" alt="Skip visual syntax diagram"
|
||
|
|
border="0" /></a> .-=-.
|
||
|
|
>>-SET--CURRENT DEGREE--+---+--+-<span class="italic">string-constant</span>-+-------------><
|
||
|
|
+-<span class="italic">variable</span>--------+
|
||
|
|
'-DEFAULT---------'
|
||
|
|
|
||
|
|
</pre>
|
||
|
|
<a name="skipsyn-379" id="skipsyn-379"></a>
|
||
|
|
<a name="synsetdegree"></a>
|
||
|
|
<h3 id="synsetdegree"><a href="rbafzmst02.htm#ToC_1294">Description</a></h3>
|
||
|
|
<p>The value of CURRENT DEGREE is replaced by the value of the
|
||
|
|
string constant or variable. The value must be a string with an actual length
|
||
|
|
that is not greater than 5 after trimming any leading and trailing blanks.
|
||
|
|
The value must be one of the following:</p>
|
||
|
|
<dl class="parml">
|
||
|
|
<dt class="bold">1</dt>
|
||
|
|
<dd>No parallel processing is allowed.
|
||
|
|
</dd>
|
||
|
|
<dt class="bold"><var class="pv">2 through 32767</var></dt>
|
||
|
|
<dd>Specifies the degree of parallelism that will be used.
|
||
|
|
</dd>
|
||
|
|
<dt class="bold">ANY</dt>
|
||
|
|
<dd>Specifies that the database manager can choose to use any number of tasks for either
|
||
|
|
I/O or SMP parallel processing.
|
||
|
|
<p>Use of parallel processing and the number
|
||
|
|
of tasks used is determined based on the number of processors available in
|
||
|
|
the system, this job's share of the amount of active memory available in the
|
||
|
|
pool in which the job is run, and whether the expected elapsed time for the
|
||
|
|
operation is limited by CPU processing or I/O resources. The database manager chooses
|
||
|
|
an implementation that minimizes elapsed time based on the job's share of
|
||
|
|
the memory in the pool.</p>
|
||
|
|
</dd>
|
||
|
|
<dt class="bold">NONE</dt>
|
||
|
|
<dd>No parallel processing is allowed.
|
||
|
|
</dd>
|
||
|
|
<dt class="bold">MAX</dt>
|
||
|
|
<dd>The database manager can choose to use any number of tasks for either I/O or SMP
|
||
|
|
parallel processing. MAX is similar to ANY except the database manager assumes that all
|
||
|
|
active memory in the pool can be used.
|
||
|
|
</dd>
|
||
|
|
<dt class="bold">IO</dt>
|
||
|
|
<dd>Any number of tasks can be used when the database manager chooses to use I/O parallel
|
||
|
|
processing for queries. SMP is not allowed.
|
||
|
|
</dd>
|
||
|
|
</dl>
|
||
|
|
<dl class="parml">
|
||
|
|
<dt class="bold"><var class="pv">variable</var></dt>
|
||
|
|
<dd>Specifies a variable that contains the value for the CURRENT DEGREE.
|
||
|
|
<p>The variable: </p>
|
||
|
|
<ul>
|
||
|
|
<li>Must be a CHAR, VARCHAR, UTF-16 or UCS-2 GRAPHIC, or UTF-16
|
||
|
|
or UCS-2 VARGRAPHIC variable. The actual length of the contents of the <var class="pv">variable</var> must not be greater than 5 after trimming any leading and trailing
|
||
|
|
blanks.</li>
|
||
|
|
<li>Must not be the null value.</li>
|
||
|
|
<li>All characters are case-sensitive and are not converted to uppercase characters.</li></ul>
|
||
|
|
</dd>
|
||
|
|
<dt class="bold"><var class="pv">string-constant</var></dt>
|
||
|
|
<dd>A character constant. The length of the constant must not exceed 5.
|
||
|
|
</dd>
|
||
|
|
<dt class="bold">DEFAULT</dt>
|
||
|
|
<dd>If the PARALLEL_DEGREE parameter in a current query options
|
||
|
|
file (QAQQINI) is specified, the CURRENT DEGREE will be reset to the PARALLEL_DEGREE.
|
||
|
|
Otherwise, the CURRENT DEGREE will be reset from the degree specified by the
|
||
|
|
QQRYDEGREE system value.
|
||
|
|
</dd>
|
||
|
|
</dl>
|
||
|
|
<a name="wq1746"></a>
|
||
|
|
<h3 id="wq1746"><a href="rbafzmst02.htm#ToC_1295">Notes</a></h3>
|
||
|
|
<p><span class="bold">Transaction considerations:</span> The SET CURRENT DEGREE
|
||
|
|
statement is not a commitable operation. ROLLBACK has no effect on CURRENT
|
||
|
|
DEGREE.</p>
|
||
|
|
<p><span class="bold">Initial current degree:</span> The initial value of CURRENT
|
||
|
|
DEGREE is equal to the parallelism degree in effect from the CHGQRYA CL command,
|
||
|
|
PARALLEL_DEGREE parameter in the current query options file (QAQQINI), or
|
||
|
|
the QQRYDEGREE system value.</p>
|
||
|
|
<p><span class="bold">Parallelism degree precedence:</span> The parallelism degree
|
||
|
|
can be controlled in several ways. The actual parallelism degree used is determined
|
||
|
|
as follows:</p>
|
||
|
|
<ul>
|
||
|
|
<li>If a SET CURRENT DEGREE statement or a CHGQRYA CL command with a DEGREE
|
||
|
|
keyword has been executed, the parallelism degree specified by the most recent
|
||
|
|
of either is the value of CURRENT DEGREE.</li>
|
||
|
|
<li>If neither a SET CURRENT DEGREE statement nor a CHGQRYA CL command with
|
||
|
|
a DEGREE keyword has been executed,
|
||
|
|
<ul>
|
||
|
|
<li>If a current query options file (QAQQINI) with a PARALLEL_DEGREE parameter
|
||
|
|
has been specified, the parallelism degree specified by the QAQQINI file is
|
||
|
|
the value of CURRENT DEGREE.</li>
|
||
|
|
<li>Otherwise, the parallelism degree specified by the QQRYDEGREE system value
|
||
|
|
is the value of CURRENT DEGREE.</li></ul></li></ul><p class="indatacontent">For more information, see <a href="../rzajq/rzajqkickoff.htm">Database Performance and
|
||
|
|
Query Optimization</a>.</p>
|
||
|
|
<p><span class="bold">Current degree scope:</span> The scope of CURRENT DEGREE
|
||
|
|
is the job.</p>
|
||
|
|
<p><span class="bold">Parallel limitations:</span> If the DB2® UDB Symmetric
|
||
|
|
Multiprocessing feature is not installed, a warning is returned and parallelism
|
||
|
|
is not used.</p>
|
||
|
|
<p>Some SQL statements cannot use parallelism.</p>
|
||
|
|
<a name="wq1747"></a>
|
||
|
|
<h3 id="wq1747"><a href="rbafzmst02.htm#ToC_1296">Example</a></h3>
|
||
|
|
<p><span class="italic">Example 1:</span> The following statement sets the CURRENT
|
||
|
|
DEGREE to inhibit parallelism.</p>
|
||
|
|
<pre class="xmp"> <span class="bold">SET CURRENT DEGREE =</span> '1' </pre>
|
||
|
|
<p><span class="italic">Example 2:</span> The following statement sets the CURRENT
|
||
|
|
DEGREE to allow parallelism.</p>
|
||
|
|
<pre class="xmp"> <span class="bold">SET CURRENT DEGREE =</span> 'ANY' </pre>
|
||
|
|
<hr /><br />
|
||
|
|
[ <a href="#Top_Of_Page">Top of Page</a> | <a href="rbafzmstsetdebug.htm">Previous Page</a> | <a href="rbafzsetdescr.htm">Next Page</a> | <a href="rbafzmst02.htm#wq1">Contents</a> |
|
||
|
|
<a href="rbafzmstindex.htm#index">Index</a> ]
|
||
|
|
|
||
|
|
<a id="Bot_Of_Page" name="Bot_Of_Page"></a>
|
||
|
|
</body>
|
||
|
|
</html>
|