142 lines
5.4 KiB
HTML
142 lines
5.4 KiB
HTML
<!DOCTYPE html>
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<html><head>
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<link href="../sqlite.css" rel="stylesheet">
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<title>Run-time Limits</title>
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<!-- path=../ -->
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</head>
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<body>
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Small. Fast. Reliable.<br>Choose any three.
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<!-- keywords: sqlite3_limit -->
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<div class=nosearch>
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<a href="intro.html"><h2>SQLite C Interface</h2></a>
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<h2>Run-time Limits</h2>
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</div>
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<blockquote><pre>
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int sqlite3_limit(sqlite3*, int id, int newVal);
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</pre></blockquote>
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<p>
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This interface allows the size of various constructs to be limited
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on a connection by connection basis. The first parameter is the
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<a href="../c3ref/sqlite3.html">database connection</a> whose limit is to be set or queried. The
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second parameter is one of the <a href="../c3ref/c_limit_attached.html">limit categories</a> that define a
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class of constructs to be size limited. The third parameter is the
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new limit for that construct.</p>
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<p>If the new limit is a negative number, the limit is unchanged.
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For each limit category SQLITE_LIMIT_<i>NAME</i> there is a
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<a href="../limits.html">hard upper bound</a>
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set at compile-time by a C preprocessor macro called
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<a href="../limits.html">SQLITE_MAX_<i>NAME</i></a>.
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(The "_LIMIT_" in the name is changed to "_MAX_".)
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Attempts to increase a limit above its hard upper bound are
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silently truncated to the hard upper bound.</p>
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<p>Regardless of whether or not the limit was changed, the
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<a href="../c3ref/limit.html">sqlite3_limit()</a> interface returns the prior value of the limit.
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Hence, to find the current value of a limit without changing it,
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simply invoke this interface with the third parameter set to -1.</p>
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<p>Run-time limits are intended for use in applications that manage
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both their own internal database and also databases that are controlled
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by untrusted external sources. An example application might be a
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web browser that has its own databases for storing history and
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separate databases controlled by JavaScript applications downloaded
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off the Internet. The internal databases can be given the
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large, default limits. Databases managed by external sources can
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be given much smaller limits designed to prevent a denial of service
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attack. Developers might also want to use the <a href="../c3ref/set_authorizer.html">sqlite3_set_authorizer()</a>
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interface to further control untrusted SQL. The size of the database
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created by an untrusted script can be contained using the
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<a href="../pragma.html#pragma_max_page_count">max_page_count</a> <a href="../pragma.html#syntax">PRAGMA</a>.</p>
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<p>New run-time limit categories may be added in future releases.
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</p><p>See also lists of
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<a href="objlist.html">Objects</a>,
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<a href="constlist.html">Constants</a>, and
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<a href="funclist.html">Functions</a>.</p>
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