Hi Scott, Yes I am suggesting the naming of the image file by ascending number (at least in part - our Sony digicam produces files named DSCnnnnn.JPG). The danger of generating a filename by hash is that collisions are always possible. Moving to an 'accession number' removes that threat.
The choice of locating the file in one or more sub-directories is a separate issue. After all, you could have one field in the db to keep track of the image's filename and another to keep track of its location - the two may or may not be related. Related: you can number/name the file and then use the last digit to determine which directory to locate it within (10 directories) - or the last two digits (100 directories). This has the advantage of spreading the directory/index load evenly as new images are 'accessioned'/arrive into the system. Non-related: you can use whatever algorithm you like, eg hashing or randomising, to decide where to place the image file. A low level of 'collisions' is immaterial in this application (whereas it would be catastrophic for image filenames)! Regards, =dn > So what you are suggesting is using an AUTO_INCREMENT field, possibly the > image's Primary Key as an identifier > for that image file., which is fine by me, but surely one should store files > across directories, as 10000 images > in a single directory might slow down access to those images in the > filesystem, or not so? > > Thanks for your input. > > Regards > > -Scott > > > -----Original Message----- > > From: DL Neil [mailto:[EMAIL PROTECTED]] > > Sent: 21 August 2002 04:31 > > To: [EMAIL PROTECTED]; Bogdan Stancescu > > Subject: Re: [PHP] Image library > > > > > > Scott (confirming Bogdan), > > > > Libraries of all types have had this concern for years - even though books > > are uniquely identified by ISBN, that is still not good enough for library > > purposes (eg multiple copies of a single title). So they, exactly > > as Bogdan > > suggests, use an "Accession" number sequence - which can be > > implemented very > > neatly in MySQL (from PHP) as an AUTO_INCREMENT field. > > > > Regards, > > =dn > > > > > I've seen this kind of random approach several times and I keep > > > wondering why not counting the files instead. Yes, it may take a little > > > longer when uploading but I personally think the safety of the approach > > > is worth the insignificant speed sacrifice. > > > > > > Bogdan > > > > > > Scott Houseman wrote: > > > > Hi all. > > > > > > > > This confirms what I suspected. > > > > > > > > The hash algrithm: > > > > > > > > I have a directory structure: dirs 0 - f, and within each of > > these, the > > same > > > > dir structure 0 - f. > > > > When an image gets uploaded into the library, do an md5sum of > > the file, > > take > > > > the first 2 chars of that hash > > > > and there's your path. e.g > > > > $PICDBPATH.'/a/7/a7b8be10b0e69fe3decaa538f1febe84' > > > > > > > > I'm not sure what the mathematical randomness of this is, but I'm sure > > it's > > > > pretty random, and the chances > > > > of collision should be virtually null, the only time you should > > overwrite a > > > > file is if you upload the exact same file(?) > > > > Is there a better way of doing this? > > > > > > > > Cheers > > > > > > > > -Scott > > > > > > > > > > > >>-----Original Message----- > > > >>From: Justin French [mailto:[EMAIL PROTECTED]] > > > >>Sent: 21 August 2002 03:25 > > > >>To: [EMAIL PROTECTED]; PHP General > > > >>Subject: Re: [PHP] Image library > > > >> > > > >> > > > >>on 21/08/02 9:45 PM, Scott Houseman ([EMAIL PROTECTED]) wrote: > > > >> > > > >> > > > >> > > > >>>Which way would be the most efficient/fastest to access images > > > >> > > > >>from an image > > > >> > > > >>>library. > > > >>>A) Store image files in a hash directory structure AND storing > > > >> > > > >>each file's > > > >> > > > >>>information in a mysql table > > > >>>OR > > > >>>B) Storing image information in mysql table AND storing the > > > >> > > > >>image in a BLOB > > > >> > > > >>>field in that table. > > > >> > > > >>>From all accounts I've read on this list, a database is not > > > >>usually faster > > > >>than a filesystem. And for large amounts of files, like 1000's, > > > >>a hash will > > > >>speed it up more. > > > >> > > > >> > > > >> > > > >>>The way I see it, considerations to be taken into acount: > > > >>>- Is it quicker/better to retrieve image from table & then stream out > > to > > > >>>browser OR simply direct the browser to the file? > > > >>>i.e <IMG SRC="/imagelib/image.php?iImageID=10"> OR <IMG > > > >>>SRC="/imagelib/5/f/10"> > > > >>>- Will a database OR filesystem be more scalable i.e. which > > wil perform > > > >>>better when there are 10000 images in the libary? > > > >> > > > >>Filesystem should be quicker. You need to think about how > > you hash the > > > >>files up for the most even spread of files in each directory I guess. > > > >> > > > >> > > > >>Justin -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
