summaryrefslogtreecommitdiffstats
path: root/www/c3ref/c_vtab_constraint_support.html
blob: ba7daadfe6f21f9ff30865a7781fb8db146665ef (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
<!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=../ -->
</head>
<body>
<div class=nosearch>
<a href="../index.html">
<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite" border="0">
</a>
<div><!-- IE hack to prevent disappearing logo --></div>
<div class="tagline desktoponly">
Small. Fast. Reliable.<br>Choose any three.
</div>
<div class="menu mainmenu">
<ul>
<li><a href="../index.html">Home</a>
<li class='mobileonly'><a href="javascript:void(0)" onclick='toggle_div("submenu")'>Menu</a>
<li class='wideonly'><a href='../about.html'>About</a>
<li class='desktoponly'><a href="../docs.html">Documentation</a>
<li class='desktoponly'><a href="../download.html">Download</a>
<li class='wideonly'><a href='../copyright.html'>License</a>
<li class='desktoponly'><a href="../support.html">Support</a>
<li class='desktoponly'><a href="../prosupport.html">Purchase</a>
<li class='search' id='search_menubutton'>
<a href="javascript:void(0)" onclick='toggle_search()'>Search</a>
</ul>
</div>
<div class="menu submenu" id="submenu">
<ul>
<li><a href='../about.html'>About</a>
<li><a href='../docs.html'>Documentation</a>
<li><a href='../download.html'>Download</a>
<li><a href='../support.html'>Support</a>
<li><a href='../prosupport.html'>Purchase</a>
</ul>
</div>
<div class="searchmenu" id="searchmenu">
<form method="GET" action="../search">
<select name="s" id="searchtype">
<option value="d">Search Documentation</option>
<option value="c">Search Changelog</option>
</select>
<input type="text" name="q" id="searchbox" value="">
<input type="submit" value="Go">
</form>
</div>
</div>
<script>
function toggle_div(nm) {
var w = document.getElementById(nm);
if( w.style.display=="block" ){
w.style.display = "none";
}else{
w.style.display = "block";
}
}
function toggle_search() {
var w = document.getElementById("searchmenu");
if( w.style.display=="block" ){
w.style.display = "none";
} else {
w.style.display = "block";
setTimeout(function(){
document.getElementById("searchbox").focus()
}, 30);
}
}
function div_off(nm){document.getElementById(nm).style.display="none";}
window.onbeforeunload = function(e){div_off("submenu");}
/* Disable the Search feature if we are not operating from CGI, since */
/* Search is accomplished using CGI and will not work without it. */
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';
b.innerHTML='show';
}else{
x.style.display = '';
b.innerHTML='hide';
}
return false;
}
var antiRobot = 0;
function antiRobotGo(){
if( antiRobot!=3 ) return;
antiRobot = 7;
var j = document.getElementById("mtimelink");
if(j && j.hasAttribute("data-href")) j.href=j.getAttribute("data-href");
}
function antiRobotDefense(){
document.body.onmousedown=function(){
antiRobot |= 2;
antiRobotGo();
document.body.onmousedown=null;
}
document.body.onmousemove=function(){
antiRobot |= 2;
antiRobotGo();
document.body.onmousemove=null;
}
setTimeout(function(){
antiRobot |= 1;
antiRobotGo();
}, 100)
antiRobotGo();
}
antiRobotDefense();
</script>
<!-- keywords: SQLITE_VTAB_CONSTRAINT_SUPPORT SQLITE_VTAB_DIRECTONLY SQLITE_VTAB_INNOCUOUS {virtual table configuration option} {virtual table configuration options} -->
<div class=nosearch>
<a href="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
</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> implmentation
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> implmentation
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>
</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>