<< I thought, if would be clever to never touch old comments
<< and just
<< update pages which are really involved to be updated.
Pages will shift as new items get inserted on top, so they all need to be
invalidated. Am I wrong?
I wouldn't try and do anything tricky unless you absolutely have to. If
query needs to be re-run every 10 min,
I don't see why bother. I would store multiple pages in cache, but that's
just so you don't have to paginate in memory upon every request.
Boris
On Tue, Sep 16, 2008 at 2:40 PM, dantro <[EMAIL PROTECTED]> wrote:
>
> @Boris
>
> my concern is following:
> a forum is a high traffic part of a website. I just thought without
> having checked,
> that for example every 10min a user posts a new comment to the forum,
> then
> every 10min the whole result set has to be set to memcache.
> therefore I thought, if would be clever to never touch old comments
> and just
> update pages which are really involved to be updated.
>
> answering your questions:
> 1. the list is ordered by timestamp DESC, therefore it is fixed
> 2. no idea. I just wanted to to plan a memcache setup which
> should be theoretically better than sending queries to mysql.
>
> On 16 Sep., 20:32, "Boris Partensky" <[EMAIL PROTECTED]>
> wrote:
> > A couple of comments:
> >
> > 1. Is the order of comments in the list (the way it is shown to a user)
> user
> > defined or is it always ordered by timestamp, most recent first? If
> latter,
> > than you can store pages of comments. So if forum id is 123, then keys
> will
> > be constructed as (123_0, 123_1, 123_2). If comments are added or
> removed,
> > then of course you need to
> > invalidate all the keys associated with that topic. If order is user
> > defined, meaning that pages may differ depending on who is looking at
> them,
> > then it's more tricky of course, because you need to keep the whole list
> in
> > memcache (and sort/create pages in memory), but you may not be able to
> keep
> > the whole thing because of memcache size limitations.
> >
> > 2. Just curious: what is your concern about running the whole comments
> list
> > query every time someone adds/removes comment? I assume there is still
> much
> > muc fewer reads than writes and you may still get tremendous gain even if
> > you invalidate the entire cache every time a topic is touched.
> > Is this query expensive? If yes, then have you looked at query plan?
> Also,
> > how many comments on average are there in a forum? Hundreds? Tens?
> >
> > Boris
> >
> >
> >
> > On Tue, Sep 16, 2008 at 1:59 PM, dantro <[EMAIL PROTECTED]> wrote:
> >
> > > dear memcache fans
> >
> > > i am looking for a solution nearly a week. my problems deals with
> > > memcache and pagination.
> >
> > > for example (without memcache):
> > > my site offers the possibility to post comments. if an user looks at
> > > the comments site i query
> > > the database via "SELECT [..] LIMIT x,y". per page I am showing 20
> > > comments. If I have 100
> > > comments it leads to 5 pages a 20 comments.
> > > Now I am looking for a solution to put these comments into memcache
> > > parallel to mysql.
> > > I don't know, understand how to deal with memcache if a comments get
> > > deleted or added.
> > > I want to prevent querying the whole comments list ("SELECT id,...
> > > WHERE forumid=$fid").
> >
> > > Do you have any solutions or what are your setups to handle memcache
> > > and mysql pagination
> > > with "LIMIT x,y" when you add or delete entries.
> >
> > > Thank you very much for helping..
> > > I really tried to find practical solutions!
> >
> > > Dan
> >
> > --
> > --Boris
>
--
--Boris
