150 lines
6.2 KiB
HTML
150 lines
6.2 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>Device Characteristics</title>
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<!-- path=../ -->
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</head>
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<body>
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<div class=nosearch>
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<a href="../index.html">
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<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite" border="0">
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</a>
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<div><!-- IE hack to prevent disappearing logo --></div>
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<div class="tagline desktoponly">
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Small. Fast. Reliable.<br>Choose any three.
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</div>
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<div class="menu mainmenu">
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<ul>
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<li><a href="../index.html">Home</a>
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<form method="GET" action="../search">
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<select name="s" id="searchtype">
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<option value="d">Search Documentation</option>
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</select>
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<input type="submit" value="Go">
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</form>
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<script>
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var w = document.getElementById(nm);
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setTimeout(function(){
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document.getElementById("searchbox").focus()
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}
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}
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function div_off(nm){document.getElementById(nm).style.display="none";}
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window.onbeforeunload = function(e){div_off("submenu");}
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/* Search is accomplished using CGI and will not work without it. */
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if( !location.origin || !location.origin.match || !location.origin.match(/http/) ){
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}
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</div>
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<!-- keywords: SQLITE_IOCAP_ATOMIC SQLITE_IOCAP_ATOMIC16K SQLITE_IOCAP_ATOMIC1K SQLITE_IOCAP_ATOMIC2K SQLITE_IOCAP_ATOMIC32K SQLITE_IOCAP_ATOMIC4K SQLITE_IOCAP_ATOMIC512 SQLITE_IOCAP_ATOMIC64K SQLITE_IOCAP_ATOMIC8K SQLITE_IOCAP_BATCH_ATOMIC SQLITE_IOCAP_IMMUTABLE SQLITE_IOCAP_POWERSAFE_OVERWRITE SQLITE_IOCAP_SAFE_APPEND SQLITE_IOCAP_SEQUENTIAL SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN -->
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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>Device Characteristics</h2>
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</div>
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<blockquote><pre>
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#define SQLITE_IOCAP_ATOMIC 0x00000001
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#define SQLITE_IOCAP_ATOMIC512 0x00000002
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#define SQLITE_IOCAP_ATOMIC1K 0x00000004
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#define SQLITE_IOCAP_ATOMIC2K 0x00000008
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#define SQLITE_IOCAP_ATOMIC4K 0x00000010
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#define SQLITE_IOCAP_ATOMIC8K 0x00000020
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#define SQLITE_IOCAP_ATOMIC16K 0x00000040
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#define SQLITE_IOCAP_ATOMIC32K 0x00000080
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#define SQLITE_IOCAP_ATOMIC64K 0x00000100
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#define SQLITE_IOCAP_SAFE_APPEND 0x00000200
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#define SQLITE_IOCAP_SEQUENTIAL 0x00000400
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#define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN 0x00000800
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#define SQLITE_IOCAP_POWERSAFE_OVERWRITE 0x00001000
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#define SQLITE_IOCAP_IMMUTABLE 0x00002000
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#define SQLITE_IOCAP_BATCH_ATOMIC 0x00004000
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</pre></blockquote>
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<p>
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The xDeviceCharacteristics method of the <a href="../c3ref/io_methods.html">sqlite3_io_methods</a>
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object returns an integer which is a vector of these
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bit values expressing I/O characteristics of the mass storage
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device that holds the file that the <a href="../c3ref/io_methods.html">sqlite3_io_methods</a>
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refers to.</p>
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<p>The SQLITE_IOCAP_ATOMIC property means that all writes of
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any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
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mean that writes of blocks that are nnn bytes in size and
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are aligned to an address which is an integer multiple of
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nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
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that when data is appended to a file, the data is appended
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first then the size of the file is extended, never the other
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way around. The SQLITE_IOCAP_SEQUENTIAL property means that
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information is written to disk in the same order as calls
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to xWrite(). The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
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after reboot following a crash or power loss, the only bytes in a
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file that were written at the application level might have changed
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and that adjacent bytes, even bytes within the same sector are
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guaranteed to be unchanged. The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
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flag indicates that a file cannot be deleted when open. The
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SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
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read-only media and cannot be changed even by processes with
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elevated privileges.</p>
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<p>The SQLITE_IOCAP_BATCH_ATOMIC property means that the underlying
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filesystem supports doing multiple write operations atomically when those
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write operations are bracketed by <a href="../c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlbeginatomicwrite">SQLITE_FCNTL_BEGIN_ATOMIC_WRITE</a> and
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<a href="../c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlcommitatomicwrite">SQLITE_FCNTL_COMMIT_ATOMIC_WRITE</a>.
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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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