MySQL ODBC Connector - are concurent queries serialized ?

Author

are concurent queries serialized ?

Bru, Pierre

2005-09-28, 8:24 pm

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hi,
=20
I run a web server on a linux box from which PHP connect to a mySQL 4 =
server running on another linux box.
tis works well but when the number of concurent connection/queries go =
high, the DB server runs very slowly.
=20
while trying to find a fix to this problem, I've been told that whatever =
the number of concurent queries the DB server receive, it process them =
thru a queue, that no more than 1 query may be performed by mySQL at a =
time.
=20
is this true ?
=20
true or not, will I gain speed by by preventing the web server to =
perform too many connections/queries at the same time? I mean, will =
10000 connection/queries be executed faster if there is at most 25 =
concurent queries than if there are 100 or more concurent =
connections/queries? (by queries, I mean a mix of select (lot) and =
update (few))
=20
TIA,
Pierre.

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Gleb Paharenko

2005-09-29, 8:23 pm

Hello.

At first, you should find out the root of the problem. Use 'SHOW
PROCESSLIST' or mysqladmin processlist (-i 1 -r options might be
helpful). See:
http://dev.mysql.com/doc/mysql/en/show-processlist.html

>1 query may be performed by mySQL at a time.
>is this true ?

It depends. But in general it is not true. InnoDB for example allows
a great concurrency. See:
http://dev.mysql.com/doc/mysql/en/innodb.html

>hi,
>
>I run a web server on a linux box from which PHP connect to a mySQL 4
server ru
nning on
>another linux box.
>tis works well but when the number of concurent connection/queries go
high, the
DB server
>runs very slowly.
>
>while trying to find a fix to this problem, I've been told that
whatever the nu
mber of
>concurent queries the DB server receive, it process them thru a queue,
that no
more than
>1 query may be performed by mySQL at a time.
>
>is this true ?
>
>true or not, will I gain speed by by preventing the web server to
perform too m
any
>connections/queries at the same time? I mean, will 10000
connection/queries be
executed
>faster if there is at most 25 concurent queries than if there are 100
or more c
oncurent
>connections/queries? (by queries, I mean a mix of select (lot) and
update (few)
)
>

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