On Jun 27, 2009, at 7:17 PM, Daniel Kolbo <kolb0057@xxxxxxx> wrote:
Phpster wrote:
Bastien
Sent from my iPod
On Jun 27, 2009, at 4:13 PM, Daniel Kolbo <kolb0057@xxxxxxx> wrote:
Ashley Sheridan wrote:
On Sat, 2009-06-27 at 16:03 -0400, Daniel Kolbo wrote:
Ashley Sheridan wrote:
On Sat, 2009-06-27 at 15:15 -0400, Daniel Kolbo wrote:
Hello,
When a MySQL table is locked a php call of mysql_query() that
requires
that table will hang as the request blocks at the MySQL server
until the
table is unlocked. Is there a way to stop a mysql_query from
hanging
(by setting a time limit)?
The php.ini directive max_execution_time does not help b/c:
"Note: The set_time_limit() function and the configuration
directive
max_execution_time only affect the execution time of the script
itself.
Any time spent on activity that happens outside the execution
of the
script such as system calls using system(), stream operations,
database
queries, etc. is not included when determining the maximum time
that the
script has been running."
The my.ini directive table_lock_wait_timeout does not work
either b/c
from MySQL:
"This variable currently is unused. "
(I am using mysql v5.1)
I do not want to bluntly stop this from the apache level.
How does one place a time limit on the execution of mysql_query
()?
Thanks for your help,
dK
It depends on what type of table you have, MyISAM blocks at table
level
for instance, while InnoDB locks at row level.
Thanks
Ash
www.ashleysheridan.co.uk
I'm using InnoDB.
But either way how do you place a time limit on mysql_query()?
Thanks,
dK
I've not seen this done before, but it should only be row locking
if
you're using InnoDB. What queries are you running that are
affecting a
script that badly?
Thanks
Ash
www.ashleysheridan.co.uk
I issue a 'lock tables tablename write' and do some work. This is
to be
expected. I want a way that to stop mysql_query() from just
waiting for
the mysql server.
`
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Further thought, do you have indexes on the table?
Bastien
Yes.
The question is not about MySQL efficiency - i'll leave that to the
MySQL email group.
This question is about putting in place PHP safe guards.
Thanks,
dK
So it's a concurrency question. There are a couple of schools of
thought here:
Flag the record on select before the update to 'lock' it to a specific
user. Any other user would get a readonly version of the data
( perhaps with a notice indicating another user has the lock )
Another common option is to accept both changes into a queue and then
deciding who's data shall be the final version.
This would add a ton of complexity fir very little gain. IMHO the
first option is better as you could build functionality to track the
record request and notify the second user when that data has been
committed and the 'lock' flag turned 'off'.
Bastien
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