ibm-information-center/dist/eclipse/plugins/i5OS.ic.ddp_5.4.0.1/rbal1block1.htm

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<h1 class="topictitle1"><span class="keyword">DB2 Universal Database™ for iSeries™</span> to <span class="keyword">DB2 Universal Database for iSeries</span> blocking</h1>
<div><div class="section"><p>Blocking will not occur if:</p>
<ul><li>The cursor is updatable (see <a href="rbal1blocksummary.htm">note
1</a>).</li>
<li>The cursor is potentially updatable (see <a href="rbal1blocksummary.htm">note
2</a>).</li>
<li>The ALWBLK(*NONE) precompile option was used.</li>
<li>The commitment control level is *CS and the level of OS/400<sup>®</sup> is earlier
than V3R1.</li>
<li>The commitment control level is *ALL and the outer subselect does not
contain one of the following items: <ul><li>The DISTINCT keyword</li>
<li>The UNION operator</li>
<li>An ORDER BY clause and the sum of the lengths of the fields in the clause
requires a sort</li>
<li>A reference to a server database file (server database files are those
in library QSYS named <samp class="codeph">QADBxxxx</samp>, and any views built over
those files)</li>
</ul>
</li>
<li>The row size is greater than approximately 2 KB or, if the <span class="cmdname">Submit
Remote Command (SBMRMTCMD)</span> command or a stored procedure was used
to extend the size of the default AS database buffer, the row size is greater
than approximately half of the size of the database buffer resulting from
specification of the <span class="cmdname">Override with Database File (OVRDBF)</span> command
SEQONLY number-of-records parameter. (Note that for the (<span class="cmdname">OVRDBF</span>)
command to work remotely, OVRSCOPE(*JOB) must be specified.)</li>
<li>The cursor is declared to be scrollable (DECLARE...SCROLL CURSOR...) and
a scroll option specified in a FETCH statement is one of the following: RELATIVE,
PRIOR, or CURRENT (unless a multiple-row FETCH was done, as mentioned previously.)</li>
</ul>
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<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="rbal1facblk.htm" title="A very important performance factor is whether blocking occurs when data is transferred between the application requester (AR) and the application server (AS). A group of rows transmitted as a block of data requires much less communications overhead than the same data sent one row at a time.">Factors that affect blocking for DRDA</a></div>
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<div class="relinfo"><strong>Related information</strong><br />
<div><a href="../cl/sbmrmtcmd.htm">Submit Remote Command (SBMRMTCMD) command</a></div>
<div><a href="../cl/ovrdbf.htm">Override with Database File (OVRDBF) command</a></div>
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