ibm-information-center/dist/eclipse/plugins/i5OS.ic.db2_5.4.0.1/rbafzmstpackageap.htm

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<h2 id="packageap"><a href="rbafzmst02.htm#ToC_38">Packages and access plans</a></h2><a id="idx106" name="idx106"></a><a id="idx107" name="idx107"></a>
<p>A <span class="italic">package</span> is an object that contains control structures
used to execute SQL statements.<sup class="fn"><a id="wq13" name="wq13" href="rbafzmstpackageap.htm#wq14">4</a></sup> Packages are produced during distributed program preparation. The control
structures can be thought of as the bound or operational form of SQL statements.
All control structures in a package are derived from the SQL statements embedded
in a single source program.</p>
<p>In this book, the term <span class="italic">access plan</span> is used in general
for packages, procedures, functions, triggers, and programs or service programs
that contain control structures used to execute SQL statements. For example,
the description of the DROP statement says that dropping an object also invalidates
any access plans that reference the object (see <a href="rbafzmstdropst.htm#dropst">DROP</a>). This
means that any packages, procedures, functions, triggers, and programs or
service programs containing control structures referencing the dropped object
are invalidated.</p>
<p>An invalidated <span class="italic">access plan</span> will be implicitly rebuilt
the next time its associated SQL statement is executed. For example, if an
index is dropped that is used in an <span class="italic">access plan</span> for
a SELECT INTO statement, the next time that SELECT INTO statement is executed,
the access plan will be rebuilt.</p>
<p>A package can also be created by the QSQPRCED API. Packages created by
the QSQPRCED API can only be used by the QSQPRCED API. They cannot be used
at an application server through DRDA&reg; protocols. For more information, see the <a href="../apis/file1.htm">i5/OS&trade; APIs</a> information in the <span class="bold">Programming</span> category
of the iSeries Information Center.</p>
<p>The QSQPRCED API is used by IBM eServer iSeries Access for Windows to create packages for caching
SQL statements executed via ODBC, JDBC, SQLJ, OLD DB, and .NET interfaces.</p>
<hr /><div class="fnnum"><a id="wq14" name="wq14" href="rbafzmstpackageap.htm#wq13">4</a>.</div>
<div class="fntext">For non-distributed SQL programs, non-distributed
service programs, SQL functions, and SQL procedures, the control structures
used to execute SQL statements are stored in the associated space of the object.</div>
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