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I'm running a website that handles multimedia uploads for one of its primary uses.
I'm wondering what are the best practices or industry standard for organizing alot of user uploaded files on a server.
Your question is exceptionally broad, but I'll assume you are talking about storage/organisation/hierarchy of the files (rather than platform/infrastructure).
A typical approach for organisation is to upload files to a 3 level hierarchical structure based on the filename itself.
Eg. Filename = "My_Video_12.mpg"
Which would then be stored in,
/M/Y/_/My_Video_12.mpg
Or another example, "a9usfkj_0001.jpg"
/a/9/u/a9usfkj_0001.jpg
This way, you end up with a manageable structure that makes it easy to locate a file's location simply based on its name. It also ensures that directories do not grow to a huge scale and become incredibly slow to access.
Just an idea, but it might be worth being more explicit as to what your question is actually about.
I don't think you are going get any concrete answers unless you give more context and describe what the use-case are for the files. Like any other technology decision, the 'best practice' is always going to be a compromise between the different functional and non-functional requirements, and as such the question needs a lot more context to yield answers that you can go and act upon.
Having said that, here are some of the strategies I would consider sound options:
1) Use the conventions dictated by the consumer of the files.
For instance, if the files are going to be used by a CMS/publishing solution, that system probably has some standardized solution for handling files.
2) Use a third party upload solution. There are a bunch of tools that can help guide you to a solution that solves your specific problem. Tools like Transloadit, Zencoder and Encoding all have different options for handling uploads. Having a look at those options should give you and idea of what could be considered "industry standard".
3) Look at proved solutions, and mimic the parts that fit your use-case. There are open-source solutions that handles the sort of things you are describing here. Have a look at the different plugins to for example paperclip, to learn how they organize files, or more importantly, what abstractions do they provide that lets you change your mind when the requirements change.
4) Design your own solution. Do a spike, it's one of the most efficient ways of exposing requirements you haven't thought about. Try integrating one of the tools mentioned above, and see how it goes. Software is soft, so no decision is final. Maybe the best solution is to just try something, and change it when it doesn't fit anymore.
This is probably not the concrete answer you were looking for, but like I mentioned in the beginning, design decisions are always a trade-off, "best-practice" in one context could be the worst solution in another context :)
Best off luck!
From what I understand you want a suggestion on how to store the files. If is that what you want, I would suggest you to have 2 different storage systems for your files.
The first storage would be a place to store the physical file, like a directory on your server (w/o FTP enabled, accessible or not to browsers, ...) or go for Amazon s3 (aws.amazon.com/en/s3/), Rackspace CloudFiles (www.rackspace.com/cloud/cloud_hosting_products/files/) or any other storage solution (you can even choose dropbox, if you want). All of these options offers APIs to save/retrieve the files.
The second storage would be a database, to index and control the files. On the DB, that could be MySQL, MSSQL or a non-relational database, like Amazon DynamoDB or SimpleSQL, you set the link to you file (http link, the path to the file or anything like this).
Also, on the DB you can control and store any metadata of the file you want and choose one or many #ebaxt's solutions to get it. The metadata can be older versions of the file, the words of a text file, the camera-model and geo-location of a picture, etc. Of course it depends on your needs and how it will be really used. You have a very large number of options, but without more info of what you intend to do is hard to suggest you a solution.
On Amazon tutorials area (http://aws.amazon.com/articles/Amazon-S3?browse=1) you can find many papers about it, like Netflix's Transition to High-Availability Storage Systems, Using the Java Persistence API with Amazon SimpleDB and Petboard: An ASP.NET Sample Using Amazon S3 and Amazon SimpleDB
Regards.
This is a design doubt am facing, I have a collection of 1500 images which are to be displayed on an asp.net page, the images to be displayed differ from one page to another, the count of these images will increase in the time to come,
a.) is it a good idea to have the images on the database, but the round trip time to fetch the images from the database might be high.
b.) is it good to have all the images on a directory, and have a virtual file system over it, and the application will access the images from the directory
Do we have in particular any design strategy in a traditional database for fetching images with the least round trip time, does any solution other than usage of a traditional database exists?
Edit 1:
Each image is replaced by its new entry for every 12 hours, so having them on the database might not be a good idea as far I can think of, but how better will it be to use a data-store and index these images?
Edit 2:
Yes, we are planning to run the application on a cluster. And if we try to use a datastore (if it is a good option to go with) then is it compatible with C# & ASP.NET?
ps: I use SQL Server to store these images.
All of the previous comments are really good... In the absence of very specific requirements we have to make broad generalizations to illustrate your options. Here are a few examples.
If raw speed is what you need, then flat files are a clear winner. Whether your using Apache or IIS, they're both optimized to serve static file-based content very fast. High performance sites all know this, and will store much of their content with dynamic handling in mind but will then "publish" select pieces of their dynamic content; in static versions; to their web farm on a periodic or event-driven basis. Although it requires a bit of orchestration, it can be done cheaply and can really reduce the load of your database server, backend network, etc. As a simple example, publish to a folder with the root of that structure being dynamically assessed. when you're ready to publish updates, write a new folder, and then change the root path. No down time, cheap, and easy. On a related note, pulling all this information from a backend store will require you to load these things into memory. This will ultimately translate to more time in Garbage Collection and consequently will mean your application is slower, even if you're using multi-processor/core gardening.
If you need fine-grained control over how images are organized/exposed, then folders may not be the most appropriate. If for example, you need to organize an individual users images and you need to track a lot of meta data around the images then a database may be a good fit. With that said, your database team will probably hate you for it, because this presents a number of challenges from a database management perspective. Additionally, if you're using an ORM you may have some trouble making this work and may find your memory footprint grows to unacceptable levels due to hidden proxy objects, second-level caching, etc. This can all be mitigated so just watch out and make sure you profile your application. With that said, a structured store (like a DB) is more ideal for this use case.
Considering security... Depending on what these images represent, flat files inevitably lead to concerns about canonicalization attacks, brute-force enumeration of browsable folder structures, replaying cookies, urls, viewstate, etc. If you're using a custom Role-based or Claims-based security model you may find using flat files becomes somewhat painful since you'll have to map filesystem security constraints to logical/contextual security constraints. Issues like these often lead me to favoring a structured store.
The aformentioned cache idea is a good one and can help create some middle-ground with respect to how often you actually hit your database, although it will not help with concerns related to memory consumption, GC, etc... You could employ built-in caching mechanisms although a Cache/Grid that supports backing stores would be much better if you can afford it (Ex. NCache, ScaleOut, etc.). These provide nice scalability/redundency, and can also be used to offload storage of session state, viewstate, and a lot more.
Hope this helps.
You basically have 2 options
1) Store the binary in the database. VARBINARY(MAX) field will be a good choice of datatype.
2) Store the path to the image stored on disk in the database. NVARCHAR(MAX) will be a good choice for datatype.
There are of course pro's and con's of both solutions. Without knowing more about your requirements Its hard to advise which is the best way.
I prefer not to store images in the database - Instead just store a link(path/filename/id etc) to the correct image.
Then if you implement a HttpHandler to serve up the images, you can store them in whatever location you like. Heres a very basic implementation:
public class myPhototHandler: IHttpHandler
{
public bool IsReusable {
get { return true; }
}
public void ProcessRequest(System.Web.HttpContext context)
{
if (Context.User.Identity.IsAuthenticated) {
var filename = context.Request.QueryString("f") ?? String.Empty;
string completePath = context.Server.MapPath(string.Format("~/App_Data/Photos/{0}", filename));
context.Response.ContentType = "image/jpeg";
context.Response.WriteFile(completePath);
}
}
}
For a great resource on setting up a handler check out this blog post and the other related posts.
I wouldn't overcomplicate your solution. The downside to storing images in a database is the database bloat and storage requirements for backups, especially if the images are only good for 12 hrs. If in doubt, keep it simple, so when requirements change, you haven't invested that much time anyways.
This is how I did it on my site.
Store the images in a folder.
If you want control over the filename the user sees, or employ conditional logic, use an HttpHandler to serve up the image, otherwise just use its full path and filename in an img tag.
If you are talking high-volume mega site, perhaps consider using a content delivery network.
Have you considered caching your images to mitigate the round-trip time to SQL server? Caching might be appropriate at the browser (via HTTP Headers) and/or the HTTP handler serving the image (via System.Web.Caching).
Storing images in SQL server can be convenient because you don't have to worry about maintaining pointers to the file system. However, the size of your database will obviously be much larger which can make backups and maintenance more complex. You might consider using a different file group within your database for your image tables, or a separate database altogether, so that you can maintain row data separate from image data.
Using SQL server also means you'll have easy options for concurrency control, partitioning and replication, should they be appropriate to your application.
A web app I'm working on requires frequent parsing of diverse web resources (HTML, XML, RSS, etc). Once downloaded, I need to cache these resources to minimize network load. The app requires a very straightforward cache policy: only re-download a cached resource when more than X minutes have passed since the access time.
Should I:
Store both the access time (e.g. 6/29/09 at 10:50 am) and the resource itself in the database.
Store the access time and a unique identifier in the database. The unique identifier is the filename of the resource, stored on the local disk.
Use another approach or third party software solution.
Essentially, this question can be re-written as, "Which is better for storing moderate amounts of data - a database or flat files?"
Thanks for your help! :)
NB: The app is running on a VPS, so size restrictions on the database/flat files do not apply.
To answer your question: "Which is better for storing moderate amounts of data - a database or flat files?"
The answer is (in my opinion) Flat Files. Flat files are easier to backup, and easier to remove.
However, you have extra information that isn't encapsulated in this question, mainly the fact that you will need to access this stored data to determine if a resource has gone stale.
Given this need, it makes more sense to store it in a database. Flat Files do not lend themselves well for random access, and search, compared to a relational DB.
Depends on the platform, IF you use .NET
The answer is 3, use Cache object, ideally suited for this in ASP.NET
You can set time and dependency expiration,
this doc explains the cache object
https://web.archive.org/web/1/http://articles.techrepublic%2ecom%2ecom/5100-10878_11-5034946.html
Neither.
Have a look at memcached to see if it works with your server/client platform. This is easier to set up and performs much better than filesystem/rdbms based caching, provided you can spare the RAM needed for the data being cached.
All of the proposed solutions are reasonable. However, for my particular needs, I went with flat files. Oddly enough, though, I did so for reasons not mentioned in some of the other answers. It doesn't really matter to me that flat files are easier to backup and remove, and both DB and flat-file solutions allow for easy checking of whether or not the cached data has gone stale. I went with flat files first and foremost because, on my mid-sized one-box VPS LAMP architecture, I think it will be faster than a third-party cache or DB-based solution.
Thanks to all for your thoughts! :)
I'm adding some functionality to my site so that users can upload their own profile pictures, so I was wondering about whether to store them in the database as a BLOB, or put them in the file system.
I found a question similar to this here: Storing images in DB: Yea or Nay, but the answers given were geared more towards people expecting many many thousands or even millions of images, whereas I'm more concerned about small images (JPEGs up to maybe 150x150 pixels), and small numbers of them: perhaps up to one or two thousand.
What are the feelings about DB BLOB vs Filesystem for this scenario? How do clients go with caching images from the DB vs from the filesystem?
If BLOBs stored in the DB are the way to go - is there anything I should know about where to store them? Since I imagine that a majority of my users won't be uploading a picture, should I create a user_pics table to (outer) join to the regular users table when needed?
Edit: I'm reopening this question, because it's not a duplicate of those two you linked to. This question is specifically about the pros/cons of using a DB or FS for a SMALL number of images. As I said above, the other question is targeted towards people who need to store thousands upon thousands of large images.
To answer parts of your question:
How do clients go with caching images from the DB vs from the filesystem?
For a database: Have a last_modified field in your database. Use the Last-Modified HTTP header so the client's browser can cache properly. Be sure to send the appropriate responses when the browser requests for an image "if newer" (can't recall what it's called; some HTTP request header).
For a filesystem: Do the same thing, but with the file's modified time.
If BLOBs stored in the DB are the way to go - is there anything I should know about where to store them? Since I imagine that a majority of my users won't be uploading a picture, should I create a user_pics table to (outer) join to the regular users table when needed?
I would put the BLOB and related metadata in its own table, with some kind of relation between it and your user table. Doing this will make it easier to optimize the table storage method for your data, makes things tidier, and leaves room for expandability (e.g. a general "files" table).
I once faced a similar question with a small DMS for pdf files. The scenario was different from yours: A maximum of may be 100 files with sizes up to 10 MB each - not what you expect for profile pictures. But the answer a friend gave me back then applies to your case as well:
Use each storage system for what it is designed to do.
Store data in a database. Store files in a file system.
This is not the ultimate answer(*), but its a good rule of thumb for starters.
I have never heard of the Windows FS being slow and sometimes unreliable, as Aaron Digulla states in his answer. If there are such problems, this certainly needs to be factored in. But for avatar pictures, it does not strike me as important.
(*) I know, I know, 42...
DB is optimized for latency, transactions, etc.
Image storage is optimized for read latency, storage cost, etc.
A blob store is ideal for storing millions of images. I work on SeaweedFS. It was based on Facebook's design for storing their user photos.
What would be more convenient, from the perspective of serving them, writing the code to serve them, backup procedures, etc.? You want the right answer for you, not the right answer for someone else.
From my point of view anything what may be left outside of database should stay outside. It may be file system or separate tables which you do not replicate or backup every day. It makes database much lighter, it grows slower and it easier to understand and maintain.
If you are on MSSQL make sure that blobs are stored in separate data file. Not in PRIMARY as everything else.
On Windows, put as much as you can in the database. The filesystem is somewhat slow and sometimes even unreliable.
On Linux, you have more options. Here, you should consider moving big files into a filesystem and just keep the name in the DB. If you use a modern filesystem like Ext3 or ReiseFS, you can even create many small files with pretty good performance.
You also need to take into account how you can access the data. If you have everything in the DB, you have one access path, need not worry about another set of permissions, but you have to deal with the extra complexity of reading/writing BLOBs. In many DBs, BLOBs can't be searched.
On the filesystem, you can run other tools on your data which isn't possible if the files are stored in a DB.
I would store them in the database:
Backup/restore is easy (if you backup files and also the database, point-in-time recovery is more complicated)
Transactions in the db mean you should never end up pointing at a file-name that is not there
Less chance someone is going to figure out a sneaky way of putting a script onto your server via a dodgy image upload hack
Since you are talking about a small number of images, ease of use/administration should take preference over performance issues which are debated in the linked questions.
I think there is a managability advantage storing them in the database; they can be backed up and restored consistently with the other data - you won't forget to delete obsolete ones (well, you might, but it's a bit less likely), and if you migrate the database to another machine, the images go with it.
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So I'm using an app that stores images heavily in the DB. What's your outlook on this? I'm more of a type to store the location in the filesystem, than store it directly in the DB.
What do you think are the pros/cons?
I'm in charge of some applications that manage many TB of images. We've found that storing file paths in the database to be best.
There are a couple of issues:
database storage is usually more expensive than file system storage
you can super-accelerate file system access with standard off the shelf products
for example, many web servers use the operating system's sendfile() system call to asynchronously send a file directly from the file system to the network interface. Images stored in a database don't benefit from this optimization.
things like web servers, etc, need no special coding or processing to access images in the file system
databases win out where transactional integrity between the image and metadata are important.
it is more complex to manage integrity between db metadata and file system data
it is difficult (within the context of a web application) to guarantee data has been flushed to disk on the filesystem
As with most issues, it's not as simple as it sounds. There are cases where it would make sense to store the images in the database.
You are storing images that are
changing dynamically, say invoices and you wanted
to get an invoice as it was on 1 Jan
2007?
The government wants you to maintain 6 years of history
Images stored in the database do not require a different backup strategy. Images stored on filesystem do
It is easier to control access to the images if they are in a database. Idle admins can access any folder on disk. It takes a really determined admin to go snooping in a database to extract the images
On the other hand there are problems associated
Require additional code to extract
and stream the images
Latency may be
slower than direct file access
Heavier load on the database server
File store. Facebook engineers had a great talk about it. One take away was to know the practical limit of files in a directory.
Needle in a Haystack: Efficient Storage of Billions of Photos
This might be a bit of a long shot, but if you're using (or planning on using) SQL Server 2008 I'd recommend having a look at the new FileStream data type.
FileStream solves most of the problems around storing the files in the DB:
The Blobs are actually stored as files in a folder.
The Blobs can be accessed using either a database connection or over the filesystem.
Backups are integrated.
Migration "just works".
However SQL's "Transparent Data Encryption" does not encrypt FileStream objects, so if that is a consideration, you may be better off just storing them as varbinary.
From the MSDN Article:
Transact-SQL statements can insert, update, query, search, and back up FILESTREAM data. Win32 file system interfaces provide streaming access to the data.
FILESTREAM uses the NT system cache for caching file data. This helps reduce any effect that FILESTREAM data might have on Database Engine performance. The SQL Server buffer pool is not used; therefore, this memory is available for query processing.
File paths in the DB is definitely the way to go - I've heard story after story from customers with TB of images that it became a nightmare trying to store any significant amount of images in a DB - the performance hit alone is too much.
In my experience, sometimes the simplest solution is to name the images according to the primary key. So it's easy to find the image that belongs to a particular record, and vice versa. But at the same time you're not storing anything about the image in the database.
The trick here is to not become a zealot.
One thing to note here is that no one in the pro file system camp has listed a particular file system. Does this mean that everything from FAT16 to ZFS handily beats every database?
No.
The truth is that many databases beat many files systems, even when we're only talking about raw speed.
The correct course of action is to make the right decision for your precise scenario, and to do that, you'll need some numbers and some use case estimates.
In places where you MUST guarantee referential integrity and ACID compliance, storing images in the database is required.
You cannot transactionaly guarantee that the image and the meta-data about that image stored in the database refer to the same file. In other words, it is impossible to guarantee that the file on the filesystem is only ever altered at the same time and in the same transaction as the metadata.
As others have said SQL 2008 comes with a Filestream type that allows you to store a filename or identifier as a pointer in the db and automatically stores the image on your filesystem which is a great scenario.
If you're on an older database, then I'd say that if you're storing it as blob data, then you're really not going to get anything out of the database in the way of searching features, so it's probably best to store an address on a filesystem, and store the image that way.
That way you also save space on your filesystem, as you are only going to save the exact amount of space, or even compacted space on the filesystem.
Also, you could decide to save with some structure or elements that allow you to browse the raw images in your filesystem without any db hits, or transfer the files in bulk to another system, hard drive, S3 or another scenario - updating the location in your program, but keep the structure, again without much of a hit trying to bring the images out of your db when trying to increase storage.
Probably, it would also allow you to throw some caching element, based on commonly hit image urls into your web engine/program, so you're saving yourself there as well.
Small static images (not more than a couple of megs) that are not frequently edited, should be stored in the database. This method has several benefits including easier portability (images are transferred with the database), easier backup/restore (images are backed up with the database) and better scalability (a file system folder with thousands of little thumbnail files sounds like a scalability nightmare to me).
Serving up images from a database is easy, just implement an http handler that serves the byte array returned from the DB server as a binary stream.
Here's an interesting white paper on the topic.
To BLOB or Not To BLOB: Large Object Storage in a Database or a Filesystem
The answer is "It depends." Certainly it would depend upon the database server and its approach to blob storage. It also depends on the type of data being stored in blobs, as well as how that data is to be accessed.
Smaller sized files can be efficiently stored and delivered using the database as the storage mechanism. Larger files would probably be best stored using the file system, especially if they will be modified/updated often. (blob fragmentation becomes an issue in regards to performance.)
Here's an additional point to keep in mind. One of the reasons supporting the use of a database to store the blobs is ACID compliance. However, the approach that the testers used in the white paper, (Bulk Logged option of SQL Server,) which doubled SQL Server throughput, effectively changed the 'D' in ACID to a 'd,' as the blob data was not logged with the initial writes for the transaction. Therefore, if full ACID compliance is an important requirement for your system, halve the SQL Server throughput figures for database writes when comparing file I/O to database blob I/O.
One thing that I haven't seen anyone mention yet but is definitely worth noting is that there are issues associated with storing large amounts of images in most filesystems too. For example if you take the approach mentioned above and name each image file after the primary key, on most filesystems you will run into issues if you try to put all of the images in one big directory once you reach a very large number of images (e.g. in the hundreds of thousands or millions).
Once common solution to this is to hash them out into a balanced tree of subdirectories.
Something nobody has mentioned is that the DB guarantees atomic actions, transactional integrity and deals with concurrency. Even referentially integrity is out of the window with a filesystem - so how do you know your file names are really still correct?
If you have your images in a file-system and someone is reading the file as you're writing a new version or even deleting the file - what happens?
We use blobs because they're easier to manage (backup, replication, transfer) too. They work well for us.
The problem with storing only filepaths to images in a database is that the database's integrity can no longer be forced.
If the actual image pointed to by the filepath becomes unavailable, the database unwittingly has an integrity error.
Given that the images are the actual data being sought after, and that they can be managed easier (the images won't suddenly disappear) in one integrated database rather than having to interface with some kind of filesystem (if the filesystem is independently accessed, the images MIGHT suddenly "disappear"), I'd go for storing them directly as a BLOB or such.
At a company where I used to work we stored 155 million images in an Oracle 8i (then 9i) database. 7.5TB worth.
Normally, I'm storngly against taking the most expensive and hardest to scale part of your infrastructure (the database) and putting all load into it. On the other hand: It greatly simplifies backup strategy, especially when you have multiple web servers and need to somehow keep the data synchronized.
Like most other things, It depends on the expected size and Budget.
We have implemented a document imaging system that stores all it's images in SQL2005 blob fields. There are several hundred GB at the moment and we are seeing excellent response times and little or no performance degradation. In addition, fr regulatory compliance, we have a middleware layer that archives newly posted documents to an optical jukebox system which exposes them as a standard NTFS file system.
We've been very pleased with the results, particularly with respect to:
Ease of Replication and Backup
Ability to easily implement a document versioning system
If this is web-based application then there could be advantages to storing the images on a third-party storage delivery network, such as Amazon's S3 or the Nirvanix platform.
Assumption: Application is web enabled/web based
I'm surprised no one has really mentioned this ... delegate it out to others who are specialists -> use a 3rd party image/file hosting provider.
Store your files on a paid online service like
Amazon S3
Moso Cloud Storage
Another StackOverflow threads talking about this here.
This thread explains why you should use a 3rd party hosting provider.
It's so worth it. They store it efficiently. No bandwith getting uploaded from your servers to client requests, etc.
If you're not on SQL Server 2008 and you have some solid reasons for putting specific image files in the database, then you could take the "both" approach and use the file system as a temporary cache and use the database as the master repository.
For example, your business logic can check if an image file exists on disc before serving it up, retrieving from the database when necessary. This buys you the capability of multiple web servers and fewer sync issues.
I'm not sure how much of a "real world" example this is, but I currently have an application out there that stores details for a trading card game, including the images for the cards. Granted the record count for the database is only 2851 records to date, but given the fact that certain cards have are released multiple times and have alternate artwork, it was actually more efficient sizewise to scan the "primary square" of the artwork and then dynamically generate the border and miscellaneous effects for the card when requested.
The original creator of this image library created a data access class that renders the image based on the request, and it does it quite fast for viewing and individual card.
This also eases deployment/updates when new cards are released, instead of zipping up an entire folder of images and sending those down the pipe and ensuring the proper folder structure is created, I simply update the database and have the user download it again. This currently sizes up to 56MB, which isn't great, but I'm working on an incremental update feature for future releases. In addition, there is a "no images" version of the application that allows those over dial-up to get the application without the download delay.
This solution has worked great to date since the application itself is targeted as a single instance on the desktop. There is a web site where all of this data is archived for online access, but I would in no way use the same solution for this. I agree the file access would be preferable because it would scale better to the frequency and volume of requests being made for the images.
Hopefully this isn't too much babble, but I saw the topic and wanted to provide some my insights from a relatively successful small/medium scale application.
SQL Server 2008 offers a solution that has the best of both worlds : The filestream data type.
Manage it like a regular table and have the performance of the file system.
It depends on the number of images you are going to store and also their sizes. I have used databases to store images in the past and my experience has been fairly good.
IMO, Pros of using database to store images are,
A. You don't need FS structure to hold your images
B. Database indexes perform better than FS trees when more number of items are to be stored
C. Smartly tuned database perform good job at caching the query results
D. Backups are simple. It also works well if you have replication set up and content is delivered from a server near to user. In such cases, explicit synchronization is not required.
If your images are going to be small (say < 64k) and the storage engine of your db supports inline (in record) BLOBs, it improves performance further as no indirection is required (Locality of reference is achieved).
Storing images may be a bad idea when you are dealing with small number of huge sized images. Another problem with storing images in db is that, metadata like creation, modification dates must handled by your application.
I have recently created a PHP/MySQL app which stores PDFs/Word files in a MySQL table (as big as 40MB per file so far).
Pros:
Uploaded files are replicated to backup server along with everything else, no separate backup strategy is needed (peace of mind).
Setting up the web server is slightly simpler because I don't need to have an uploads/ folder and tell all my applications where it is.
I get to use transactions for edits to improve data integrity - I don't have to worry about orphaned and missing files
Cons:
mysqldump now takes a looooong time because there is 500MB of file data in one of the tables.
Overall not very memory/cpu efficient when compared to filesystem
I'd call my implementation a success, it takes care of backup requirements and simplifies the layout of the project. The performance is fine for the 20-30 people who use the app.
Im my experience I had to manage both situations: images stored in database and images on the file system with path stored in db.
The first solution, images in database, is somewhat "cleaner" as your data access layer will have to deal only with database objects; but this is good only when you have to deal with low numbers.
Obviously database access performance when you deal with binary large objects is degrading, and the database dimensions will grow a lot, causing again performance loss... and normally database space is much more expensive than file system space.
On the other hand having large binary objects stored in file system will cause you to have backup plans that have to consider both database and file system, and this can be an issue for some systems.
Another reason to go for file system is when you have to share your images data (or sounds, video, whatever) with third party access: in this days I'm developing a web app that uses images that have to be accessed from "outside" my web farm in such a way that a database access to retrieve binary data is simply impossible. So sometimes there are also design considerations that will drive you to a choice.
Consider also, when making this choice, if you have to deal with permission and authentication when accessing binary objects: these requisites normally can be solved in an easier way when data are stored in db.
I once worked on an image processing application. We stored the uploaded images in a directory that was something like /images/[today's date]/[id number]. But we also extracted the metadata (exif data) from the images and stored that in the database, along with a timestamp and such.
In a previous project i stored images on the filesystem, and that caused a lot of headaches with backups, replication, and the filesystem getting out of sync with the database.
In my latest project i'm storing images in the database, and caching them on the filesystem, and it works really well. I've had no problems so far.
Second the recommendation on file paths. I've worked on a couple of projects that needed to manage large-ish asset collections, and any attempts to store things directly in the DB resulted in pain and frustration long-term.
The only real "pro" I can think of regarding storing them in the DB is the potential for easy of individual image assets. If there are no file paths to use, and all images are streamed straight out of the DB, there's no danger of a user finding files they shouldn't have access to.
That seems like it would be better solved with an intermediary script pulling data from a web-inaccessible file store, though. So the DB storage isn't REALLY necessary.
The word on the street is that unless you are a database vendor trying to prove that your database can do it (like, let's say Microsoft boasting about Terraserver storing a bajillion images in SQL Server) it's not a very good idea. When the alternative - storing images on file servers and paths in the database is so much easier, why bother? Blob fields are kind of like the off-road capabilities of SUVs - most people don't use them, those who do usually get in trouble, and then there are those who do, but only for the fun of it.
Storing an image in the database still means that the image data ends up somewhere in the file system but obscured so that you cannot access it directly.
+ves:
database integrity
its easy to manage since you don't have to worry about keeping the filesystem in sync when an image is added or deleted
-ves:
performance penalty -- a database lookup is usually slower that a filesystem lookup
you cannot edit the image directly (crop, resize)
Both methods are common and practiced. Have a look at the advantages and disadvantages. Either way, you'll have to think about how to overcome the disadvantages. Storing in database usually means tweaking database parameters and implement some kind of caching. Using filesystem requires you to find some way of keeping filesystem+database in sync.