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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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<a href="intro.html"><h2>SQLite C Interface</h2></a>
<h2>Device Characteristics</h2>
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<blockquote><pre>
#define SQLITE_IOCAP_ATOMIC 0x00000001
#define SQLITE_IOCAP_ATOMIC512 0x00000002
#define SQLITE_IOCAP_ATOMIC1K 0x00000004
#define SQLITE_IOCAP_ATOMIC2K 0x00000008
#define SQLITE_IOCAP_ATOMIC4K 0x00000010
#define SQLITE_IOCAP_ATOMIC8K 0x00000020
#define SQLITE_IOCAP_ATOMIC16K 0x00000040
#define SQLITE_IOCAP_ATOMIC32K 0x00000080
#define SQLITE_IOCAP_ATOMIC64K 0x00000100
#define SQLITE_IOCAP_SAFE_APPEND 0x00000200
#define SQLITE_IOCAP_SEQUENTIAL 0x00000400
#define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN 0x00000800
#define SQLITE_IOCAP_POWERSAFE_OVERWRITE 0x00001000
#define SQLITE_IOCAP_IMMUTABLE 0x00002000
#define SQLITE_IOCAP_BATCH_ATOMIC 0x00004000
</pre></blockquote>
<p>
The xDeviceCharacteristics method of the <a href="../c3ref/io_methods.html">sqlite3_io_methods</a>
object returns an integer which is a vector of these
bit values expressing I/O characteristics of the mass storage
device that holds the file that the <a href="../c3ref/io_methods.html">sqlite3_io_methods</a>
refers to.</p>
<p>The SQLITE_IOCAP_ATOMIC property means that all writes of
any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
mean that writes of blocks that are nnn bytes in size and
are aligned to an address which is an integer multiple of
nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
that when data is appended to a file, the data is appended
first then the size of the file is extended, never the other
way around. The SQLITE_IOCAP_SEQUENTIAL property means that
information is written to disk in the same order as calls
to xWrite(). The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
after reboot following a crash or power loss, the only bytes in a
file that were written at the application level might have changed
and that adjacent bytes, even bytes within the same sector are
guaranteed to be unchanged. The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
flag indicates that a file cannot be deleted when open. The
SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
read-only media and cannot be changed even by processes with
elevated privileges.</p>
<p>The SQLITE_IOCAP_BATCH_ATOMIC property means that the underlying
filesystem supports doing multiple write operations atomically when those
write operations are bracketed by <a href="../c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlbeginatomicwrite">SQLITE_FCNTL_BEGIN_ATOMIC_WRITE</a> and
<a href="../c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlcommitatomicwrite">SQLITE_FCNTL_COMMIT_ATOMIC_WRITE</a>.
</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>
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