I know a lot more about DB2, my main database, than MySQL. However, MySQL
frequently does the same things in the same ways as DB2.
_If_ MySQL behaves the same way as DB2 in this regard - and I do not know if
it does - there is no function to determine if a given resource is locked.
Instead, the program which is trying to get a lock but fails because another
program has the necessary lock simply waits for a set amount of time. If the
resource (table, row, or whatever) gets unlocked before the clock runs out,
the waiting programs are permitted to try to get their own locks on the
resource, basically on a first-come, first-served manner. If the clock runs
out before the resource has been released by the first program, the waiting
program(s) get return codes and messages that indicate that they timed out
and what resource was not available. At that point, the program can decide
to try again, as many times as it likes, or to give up. The timeout interval
can be set/changed by the system administrator.
Again, let me stress that this is how DB2 behaves. MySQL may very well
behave differently. However, I have noticed a great many similarities
between DB2 and MySQL so they may behave the same in this regard too. I'm
looking forward to seeing other answers to your question from people who
know exactly how MySQL behaves in this regard so that I can learn more about
MySQL.
Rhino
----- Original Message -----
From: "wang shuming" <[EMAIL PROTECTED]>
To: <mysql@lists.mysql.com>
Sent: Friday, November 18, 2005 11:06 PM
Subject: what function could detect a row locked by other client ?
Hi,
I know select .. update could lock selected rows, if the connection not
release the lock, others always wait.
If I use get_lock() to get a logical lock by key xxxtable+xxxrow , but
others may not update other database on the same server .
What function could detect a row locked (by select ... update) by other
client ?
Best regard!
Shuming Wang
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