Oracle 5.0 Reference Manual page 986

-> NULL
The second
RELEASE_LOCK()
automatically released by the second
If multiple clients are waiting for a lock, the order in which they will acquire it is undefined and
depends on factors such as the thread library in use. In particular, applications should not assume
that clients will acquire the lock in the same order that they issued the lock requests.
Note
If a client attempts to acquire a lock that is already held by another client, it
blocks according to the
its thread does not die until the lock request times out. This is a known bug
(fixed in MySQL 5.5).
•
INET_ATON(expr)
Given the dotted-quad representation of an IPv4 network address as a string, returns an
integer that represents the numeric value of the address in network byte order (big endian).
[966]
INET_ATON()
mysql> SELECT INET_ATON('10.0.5.9');
-> 167773449
For this example, the return value is calculated as 10×256
[966]
INET_ATON()
as a representation of '127.0.0.1'). Because of this,
'127.1'
be used for such addresses.
Note
To store values generated by
column rather than INT, which is signed. If you use a signed column, values
corresponding to IP addresses for which the first octet is greater than 127
cannot be stored correctly. See
Handling".
•
INET_NTOA(expr)
Given a numeric IPv4 network address in network byte order, returns the dotted-quad representation
of the address as a binary string.
argument.
mysql> SELECT INET_NTOA(167773449);
-> '10.0.5.9'
•
IS_FREE_LOCK(str)
Checks whether the lock named
(no one is using the lock),
argument).
•
IS_USED_LOCK(str)
Checks whether the lock named
identifier of the client that holds the lock. Otherwise, it returns NULL.
•
MASTER_POS_WAIT(log_name,log_pos[,timeout])
This function is useful for control of master/slave synchronization. It blocks until the slave has read
and applied all updates up to the specified position in the master log. The return value is the number
Miscellaneous Functions
[967] call returns
GET_LOCK()
timeout
[966]
returns if it does not understand its argument.
NULL
may or may not return a
[966]
INET_NTOA()
[966]
is free to use (that is, not locked). Returns
str
if the lock is in use, and
0
[966]
is in use (that is, locked). If so, it returns the connection
str
966
because the lock
NULL
[965] call.
argument. If the blocked client terminates,
3 2
+ 0×256
non-NULL result for short-form IP addresses (such as
INET_ATON()
[966], use an
INET_ATON()
Section 11.1.4.6, "Out-of-Range and Overflow
[966] returns
NULL
if an error occurs (such as an incorrect
NULL
[966]
was
'lock1'
+ 5×256 + 9.
[966]a should not
INT UNSIGNED
if it does not understand its
if the lock is free
1