Alessandro Bonazzi 5c7aa8c1c0 Patch level : 12.0 no-patch
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Aggiunta documentazione di sqlite 3
2020-11-29 00:32:36 +01:00

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<!-- keywords: {*limit categories} SQLITE_LIMIT_ATTACHED SQLITE_LIMIT_COLUMN SQLITE_LIMIT_COMPOUND_SELECT SQLITE_LIMIT_EXPR_DEPTH SQLITE_LIMIT_FUNCTION_ARG SQLITE_LIMIT_LENGTH SQLITE_LIMIT_LIKE_PATTERN_LENGTH SQLITE_LIMIT_SQL_LENGTH SQLITE_LIMIT_TRIGGER_DEPTH SQLITE_LIMIT_VARIABLE_NUMBER SQLITE_LIMIT_VDBE_OP SQLITE_LIMIT_WORKER_THREADS {limit category} -->
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<a href="intro.html"><h2>SQLite C Interface</h2></a>
<h2>Run-Time Limit Categories</h2>
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<blockquote><pre>
#define SQLITE_LIMIT_LENGTH 0
#define SQLITE_LIMIT_SQL_LENGTH 1
#define SQLITE_LIMIT_COLUMN 2
#define SQLITE_LIMIT_EXPR_DEPTH 3
#define SQLITE_LIMIT_COMPOUND_SELECT 4
#define SQLITE_LIMIT_VDBE_OP 5
#define SQLITE_LIMIT_FUNCTION_ARG 6
#define SQLITE_LIMIT_ATTACHED 7
#define SQLITE_LIMIT_LIKE_PATTERN_LENGTH 8
#define SQLITE_LIMIT_VARIABLE_NUMBER 9
#define SQLITE_LIMIT_TRIGGER_DEPTH 10
#define SQLITE_LIMIT_WORKER_THREADS 11
</pre></blockquote>
<p>
These constants define various performance limits
that can be lowered at run-time using <a href="../c3ref/limit.html">sqlite3_limit()</a>.
The synopsis of the meanings of the various limits is shown below.
Additional information is available at <a href="../limits.html">Limits in SQLite</a>.</p>
<p><dl>
<a name="sqlitelimitlength"></a>
<dt>SQLITE_LIMIT_LENGTH</dt>
<dd>The maximum size of any string or BLOB or table row, in bytes.<dd></p>
<p><a name="sqlitelimitsqllength"></a>
<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
<dd>The maximum length of an SQL statement, in bytes.</dd></p>
<p><a name="sqlitelimitcolumn"></a>
<dt>SQLITE_LIMIT_COLUMN</dt>
<dd>The maximum number of columns in a table definition or in the
result set of a <a href="../lang_select.html">SELECT</a> or the maximum number of columns in an index
or in an ORDER BY or GROUP BY clause.</dd></p>
<p><a name="sqlitelimitexprdepth"></a>
<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
<dd>The maximum depth of the parse tree on any expression.</dd></p>
<p><a name="sqlitelimitcompoundselect"></a>
<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
<dd>The maximum number of terms in a compound SELECT statement.</dd></p>
<p><a name="sqlitelimitvdbeop"></a>
<dt>SQLITE_LIMIT_VDBE_OP</dt>
<dd>The maximum number of instructions in a virtual machine program
used to implement an SQL statement. If <a href="../c3ref/prepare.html">sqlite3_prepare_v2()</a> or
the equivalent tries to allocate space for more than this many opcodes
in a single prepared statement, an SQLITE_NOMEM error is returned.</dd></p>
<p><a name="sqlitelimitfunctionarg"></a>
<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
<dd>The maximum number of arguments on a function.</dd></p>
<p><a name="sqlitelimitattached"></a>
<dt>SQLITE_LIMIT_ATTACHED</dt>
<dd>The maximum number of <a href="../lang_attach.html">attached databases</a>.</dd></p>
<p><a name="sqlitelimitlikepatternlength"></a>
<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
<dd>The maximum length of the pattern argument to the <a href="../lang_expr.html#like">LIKE</a> or
<a href="../lang_expr.html#glob">GLOB</a> operators.</dd></p>
<p><a name="sqlitelimitvariablenumber"></a>
<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
<dd>The maximum index number of any <a href="../lang_expr.html#varparam">parameter</a> in an SQL statement.</p>
<p><a name="sqlitelimittriggerdepth"></a>
<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
<dd>The maximum depth of recursion for triggers.</dd></p>
<p><a name="sqlitelimitworkerthreads"></a>
<dt>SQLITE_LIMIT_WORKER_THREADS</dt>
<dd>The maximum number of auxiliary worker threads that a single
<a href="../c3ref/stmt.html">prepared statement</a> may start.</dd>
</dl>
</p><p>See also lists of
<a href="objlist.html">Objects</a>,
<a href="constlist.html">Constants</a>, and
<a href="funclist.html">Functions</a>.</p>