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+<!DOCTYPE html>
+<html><head>
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<link href="../sqlite.css" rel="stylesheet">
+<title>Virtual Table Configuration Options</title>
+<!-- path=../ -->
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+<body>
+<div class=nosearch>
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+<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite" border="0">
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+if( !location.origin || !location.origin.match || !location.origin.match(/http/) ){
+document.getElementById("search_menubutton").style.display = "none";
+}
+/* Used by the Hide/Show button beside syntax diagrams, to toggle the */
+function hideorshow(btn,obj){
+var x = document.getElementById(obj);
+var b = document.getElementById(btn);
+if( x.style.display!='none' ){
+x.style.display = 'none';
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+<!-- keywords: SQLITE_VTAB_CONSTRAINT_SUPPORT SQLITE_VTAB_DIRECTONLY SQLITE_VTAB_INNOCUOUS SQLITE_VTAB_USES_ALL_SCHEMAS {virtual table configuration option} {virtual table configuration options} -->
+<div class=nosearch>
+<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a>
+<h2>Virtual Table Configuration Options</h2>
+</div>
+<blockquote><pre>
+#define SQLITE_VTAB_CONSTRAINT_SUPPORT 1
+#define SQLITE_VTAB_INNOCUOUS 2
+#define SQLITE_VTAB_DIRECTONLY 3
+#define SQLITE_VTAB_USES_ALL_SCHEMAS 4
+</pre></blockquote>
+<p>
+These macros define the various options to the
+<a href="../c3ref/vtab_config.html">sqlite3_vtab_config()</a> interface that <a href="../vtab.html">virtual table</a> implementations
+can use to customize and optimize their behavior.</p>
+
+<p><dl>
+<a name="sqlitevtabconstraintsupport"></a>
+
+<dt>SQLITE_VTAB_CONSTRAINT_SUPPORT</dt>
+<dd>Calls of the form
+<a href="../c3ref/vtab_config.html">sqlite3_vtab_config</a>(db,SQLITE_VTAB_CONSTRAINT_SUPPORT,X) are supported,
+where X is an integer. If X is zero, then the <a href="../vtab.html">virtual table</a> whose
+<a href="../vtab.html#xcreate">xCreate</a> or <a href="../vtab.html#xconnect">xConnect</a> method invoked <a href="../c3ref/vtab_config.html">sqlite3_vtab_config()</a> does not
+support constraints. In this configuration (which is the default) if
+a call to the <a href="../vtab.html#xupdate">xUpdate</a> method returns <a href="../rescode.html#constraint">SQLITE_CONSTRAINT</a>, then the entire
+statement is rolled back as if <a href="../lang_conflict.html">OR ABORT</a> had been
+specified as part of the users SQL statement, regardless of the actual
+ON CONFLICT mode specified.</p>
+
+<p>If X is non-zero, then the virtual table implementation guarantees
+that if <a href="../vtab.html#xupdate">xUpdate</a> returns <a href="../rescode.html#constraint">SQLITE_CONSTRAINT</a>, it will do so before
+any modifications to internal or persistent data structures have been made.
+If the <a href="../lang_conflict.html">ON CONFLICT</a> mode is ABORT, FAIL, IGNORE or ROLLBACK, SQLite
+is able to roll back a statement or database transaction, and abandon
+or continue processing the current SQL statement as appropriate.
+If the ON CONFLICT mode is REPLACE and the <a href="../vtab.html#xupdate">xUpdate</a> method returns
+<a href="../rescode.html#constraint">SQLITE_CONSTRAINT</a>, SQLite handles this as if the ON CONFLICT mode
+had been ABORT.</p>
+
+<p>Virtual table implementations that are required to handle OR REPLACE
+must do so within the <a href="../vtab.html#xupdate">xUpdate</a> method. If a call to the
+<a href="../c3ref/vtab_on_conflict.html">sqlite3_vtab_on_conflict()</a> function indicates that the current ON
+CONFLICT policy is REPLACE, the virtual table implementation should
+silently replace the appropriate rows within the xUpdate callback and
+return SQLITE_OK. Or, if this is not possible, it may return
+SQLITE_CONSTRAINT, in which case SQLite falls back to OR ABORT
+constraint handling.
+</dd></p>
+
+<p><a name="sqlitevtabdirectonly"></a>
+<dt>SQLITE_VTAB_DIRECTONLY</dt>
+<dd>Calls of the form
+<a href="../c3ref/vtab_config.html">sqlite3_vtab_config</a>(db,SQLITE_VTAB_DIRECTONLY) from within the
+the <a href="../vtab.html#xconnect">xConnect</a> or <a href="../vtab.html#xcreate">xCreate</a> methods of a <a href="../vtab.html">virtual table</a> implementation
+prohibits that virtual table from being used from within triggers and
+views.
+</dd></p>
+
+<p><a name="sqlitevtabinnocuous"></a>
+<dt>SQLITE_VTAB_INNOCUOUS</dt>
+<dd>Calls of the form
+<a href="../c3ref/vtab_config.html">sqlite3_vtab_config</a>(db,SQLITE_VTAB_INNOCUOUS) from within the
+the <a href="../vtab.html#xconnect">xConnect</a> or <a href="../vtab.html#xcreate">xCreate</a> methods of a <a href="../vtab.html">virtual table</a> implementation
+identify that virtual table as being safe to use from within triggers
+and views. Conceptually, the SQLITE_VTAB_INNOCUOUS tag means that the
+virtual table can do no serious harm even if it is controlled by a
+malicious hacker. Developers should avoid setting the SQLITE_VTAB_INNOCUOUS
+flag unless absolutely necessary.
+</dd></p>
+
+<p><a name="sqlitevtabusesallschemas"></a>
+<dt>SQLITE_VTAB_USES_ALL_SCHEMAS</dt>
+<dd>Calls of the form
+<a href="../c3ref/vtab_config.html">sqlite3_vtab_config</a>(db,SQLITE_VTAB_USES_ALL_SCHEMA) from within the
+the <a href="../vtab.html#xconnect">xConnect</a> or <a href="../vtab.html#xcreate">xCreate</a> methods of a <a href="../vtab.html">virtual table</a> implementation
+instruct the query planner to begin at least a read transaction on
+all schemas ("main", "temp", and any ATTACH-ed databases) whenever the
+virtual table is used.
+</dd>
+</dl>
+</p><p>See also lists of
+ <a href="../c3ref/objlist.html">Objects</a>,
+ <a href="../c3ref/constlist.html">Constants</a>, and
+ <a href="../c3ref/funclist.html">Functions</a>.</p>
+