On Mon, Feb 15, 2010 at 10:53 AM, Martijn Tonies <m.ton...@upscene.com>wrote:
> databases are made for storing data - it saves you on both database and PHP >> requests, as (from a web point of view) you can't return the image data >> inside your HTML - it requires a second HTTP call. Filesystem image >> serving, >> > > Doesn't an image always required additional http calls from the <IMG> tag? Yes, that's what I'm saying. However, there's a significant difference between an HTTP call that only needs to pump a file on to the network, and an HTTP call that needs to start a PHP process that then in turn needs to connect to the DB, which then needs to parse and execute a query. Offloading static files (images, css, whatnot) to a separate server that runs a lightweight, threaded httpd without PHP and whatnot compiled in, also means that you'll need less hardware to serve the same amount of requests - our PHP machines typically run 400 apache processes, but a static server on the same hardware could easily serve a few thousand threads - suddenly it's not memory/cpu but disk/network bandwidth that becomes your bottleneck. > If you do go for BLOBs, though, for god's sake keep them in a separate >> table, lest you fragment your datafiles. Split records are a disaster for >> performance. >> > > I agree -for MySQL-, but this is a MySQL limitation!! Not a DBMS one. True. I think (but am too lazy to verify) that even in MySQL this is mainly an issue with MyISAM, not InnoDB. Given how MyISAM is the default engine, though, I thought it worthwile to mention. Separate LOB storage still leaves the overhead of query parsing and other generic DBMS stuff which isn't there on a filesystem, though, not to mention that each image requests takes up a database connection for as long as it takes to transfer the (potentially huge) data. Don't forget that in a well-tuned database, network transfer is often a significant part of your total connection lifetime for select statements. -- Bier met grenadyn Is als mosterd by den wyn Sy die't drinkt, is eene kwezel Hy die't drinkt, is ras een ezel
