El Jue 25 Ene 2001 14:34, Frank Joerdens escribió:
> On Thu, Jan 25, 2001 at 11:18:49AM -0300, Martin A. Marques wrote:
> [ . . . ]
>
> > No, and thats why in the postgres list we talked about persistent
> > connections not having much benefits. That is because the connection is
> > persistent to the httpd child that called it and not to all.
>
> Well, yes, but as long as the child lives, it'll be connected which
> means that every subsequent request to this child involving a database
> connection won't have to suffer the connection startup cost. If you have
> a rather inexpensive query, and a lot of web apps use simple,
> straightforward selects that are very inexpensive, then the connection
> startup overhead contributes more to the performance hit than the actual
> query.
Of course. But the persistent connection are not working as the manuals say
they should work.
> [ . . . ]
>
> > Now be carefull. http connection open and close, they do not stay open,
> > so if you try to execute different SQL statments with different httpd
> > connections, your gonna have trouble (the sql server won't let you,
> > because there is another transaction been executed).
>
> Hmm. Say the Apache child is idle (under which cirumstances exactly does
> it consider itself 'idle'?), receives a request for a page which
> executes a query (because it contains php code that does). This takes a
> while. In the meantime, while the SQL server is chugging away running
> the query, will the Apache child not accept further http requests? How
> does the Apache child know that it is waiting for the query to complete?
> This is what I don't know about the mechanism.
That has nothing to do with apache. If the SQL statments are well
implemented, the second query wouldn't see any of the changes that the first
query executed until the work is commited, and it shouldn't be able to modify
the rows with which the first query is updating or deleting.
But thats Postgres that doesn't let it, not the apache server, not php.
Saludos... :-)
--
System Administration: It's a dirty job,
but someone told I had to do it.
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Martín Marqués email: [EMAIL PROTECTED]
Santa Fe - Argentina http://math.unl.edu.ar/~martin/
Administrador de sistemas
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