The Catalog

The catalog is the information hub of LIghtroom. There seems to be a lot of confusing folklore about it. Let’s talk about the catalog and demystify it some.

This is specific to Lightroom Classic. Other tools exist. I do not know them and can’t discuss them. I believe Lightroom is the most widely used image management tool.

A database

When I refer to Lightroom, I mean Lightroom Classic. It is the only useful version for me. So be aware I do not discuss the cloud behavior of Lightroom at all.

Lightroom is both a file management tool and a raw file editor. I’ve discussed raw editing before, so this article will just be about file management. We tend to shoot a lot of images these days. Without a way to organize all these and search for the ones we want, they become almost useless. How do you locate the right file when you need it?

We do it with Lightroom and its catalog. The catalog is a database. I know that is a scary term to some, but it just means it is a file on the computer. The catalog in Lightgroom Classic is stored locally on your computer. It has a particular structure and capabilities that let Lightroom enter information about each image and rapidly search for it.

So the Lightroom catalog holds a lot of data about our images. Some that it reads when we import our images and some that we tell it manually, like keywords and ratings and collection groupings. What the catalog does not contain is images.

None of our images are actually stored in the catalog. They stay in our computer’s file system, wherever we decide to put them, as ordinary image files. They can be on any of our disks, internal or external. The catalog only notes their location and keeps track of it so it can call up images for us in the Lightroom screen.

Where are the images?

I mentioned some of the things the catalog contains. Let’s be more specific. I said the catalog does not contain any images. As you import images into Lightroom you choose where they will be stored. LIghtroom records the location about where each images is in the file structure of your computer. For instance, taking a random file that I happened to be looking at a few minutes ago, the path and file name is:

/Volumes/LaCie-raid/Images/Images/New Mexico/Eastern I-40/Tucumcari/20231110-259.NEF

This is the image above. This is what Lightroom has in the catalog instead of the image. Why? Because the file system of your operating system does an excellent job of managing its disks reliably and speedily. Lightroom does not try to duplicate that. Also, the file above is 52.4 MBytes. Let’s say you had 100,000 images this size stored in your catalog. Over 5TBytes of storage becomes impractical and would overflow a lot of people’s hard drive. And many people’s catalogs are much larger than that. Also, leaving the individual files visible allows us to use other tools to manipulate them.

As I browse in Lightroom, when I come to where I want to look at this image, LIghtroom goes to the noted location on my disk and reads the image file and displays it. Actually, it first looks first in a special place where LIghtroom caches previews to see if there is a faster way to view it, but that is getting too deep for now.


In addition, there is what is called metadata. This is just a computer science term meaning data about data. In our case, it is information read from the camera when the file was imported and information we have added manually.

Examples of automatically gathered data are the camera used, including it’s serial number, the lens used., how the image was metered and exposed, the ISO. Also recorded is the dimensions, the data it was captured and many other details.

Information we enter can include creator name, copyright information, keywords, rating, a title, a label, a caption, location, and other things. In addition, as we edit an image, all of the edit settings are recorded, from simple things like adjusting exposure to complex masks and adjustments. Virtual files are just copies of a files’ data in the catalog with a different set of metadata, not a duplicate of the file itself. And all Collections we create are simply sets of data in the catalog. Again, no copies of the files are made to create a Collection.

The catalog holds a lot of data. It is a very important piece of Lightroom and is key to letting the whole thing work.

How many catalogs?

One of the first decisions to make when setting up Lightroom is how many catalogs to have. We could have a separate catalog for each type of content or activity. For instance, one for family photos, one for fine art, one for weddings, one for travel, etc. This initially seems logical to keep things separate and minimize the size of each catalog.

My advice is don’t do it. Resist the temptation to have multiple catalogs. It will just make it harder to organize your work and harder to locate something. It might seem like a good idea to minimize the number of images in a catalog, but as far as I can tell, it doesn’t matter. I have over 130,000 images in my catalog. That is small compared to many other photographers. I am comfortable with throwing away images I deem worthless or exact duplicates. Other people don’t. But that is another discussion.

I put extensive metadata in, such as location information, keywords, ratings, titles, and captions. And I do most of my image editing in Lightroom. This greatly expands the amount of metadata. The point is that this number of images does not appear to cause any stress or slowdown in my Lightroom catalog. I know of photographers who have catalogs several times larger.

Don’t do this

As a “don’t do this” anecdote, I have a friend who decided he knew better than Adobe and was going to manage his data more closely. He set up a catalog for each hard drive he had. As he outgrew a disk and added another one, it was a new catalog. Consequently, he has a data nightmare. It is very difficult for him to locate something unless he can remember exactly when it was shot and consequently what disk and catalog it is on.

I strongly recommend you use 1 catalog and upgrade to larger disks as you run out of space. Yes, Lightroom can manage files across multiple disks, but you probably don’t want the bother. Disks wear out and need to be replaced anyway.

How to organize it?

How you organize your files is a personal decision. You need to figure out how you think about your data and how you “self organize”. You can see several things about my organization decisions from the example I gave of the file location data LIghtroom records. Most of my files are organized geographically. And my file naming is mostly centered on dates. It is not important to me to name images by their content. That is what Lightroom is for.

All my images are stored on 1 fairly fast RAID disk drive. My feeling is this is easy for me to know where things are and easy to organize my backup strategy. The catalog itself is on an external fast SSD. The catalog is heavily used and this made a large improvement in performance.

Be fanatical about backup! Your data is important. I use a combination of Time Machine – one of the greatest inventions in the history of computers – and a rigorous backup strategy using Carbon Copy Cloner. I do not receive any compensation from them for saying this. There are 2 external backup disks attached to my computer and another network attached RAID disk physically separate within my studio. I also backup to small hard disks that I rotate to offsite locations.

So do you have to adopt any of the organization I use? Absolutely not. Every instructor probably has their own unique recommendation that is adapted to their needs and preferences. As I said, it is a personal decision. But it is a decision you have to make. Decide on your strategy and stick with it religiously. It will pay you benefits.

Do all file operations from Lightroom

Have you ever seen a “?” in place of an image? That is because Lightroom could not find the file. This is usually because a disk drive is offline or you moved some files using your computer file manager. Lightroom can’t locate the file and the best it can do is show a preview if it has one and mark it with the “?” to indicate it needs to be located. Locating a moved image is easy, but it is easier to avoid the problem entirely.

Always do all of your file management from within Lightroom. Always! Lightroom has to know the location of each file it manages. It has very good capabilities for creating folders and moving files and folders around. It does the work of moving them on your computer file system and remembers the locations. And It is probably even faster and easier to move a large group of files from LIghtroom than it is using your computers file manager.

All the eggs in one basket?

If all your data is in the catalog, aren’t you at risk if it gets corrupted or erased? Yes. But there are many ways to mitigate this.

LIghtroom has settings to automatically backup its catalog. Use that. Second, use other backup solutions like Time Machine and Carbon Copy Cloner to do your own backups.

Third, you can optionally have most of your metadata also saved to files alongside your image files. These are known as sidecar files and have the extension “.xmp”. I turn on this capability. If the catalog is lost or corrupted it is possible to recover most of my data to a new catalog by importing the images and these sidecar files. This is a topic for another article.

And lastly, I have been using Lightroom full time starting with its original beta release. Adobe has done a marvelous job of reliably keeping my data in tact. This is not a guarantee of future behavior, but so far they have earned my trust.


The Lightroom Classic catalog is a database stored locally on your computer. It is well established, good technology. Not magic.

We do not see the catalog as a database, we do not have to know about databases, and we do not need to know much about searching databases. All that is wrapped in the Lightroom program. But knowing a little about how it works makes managing it easier.

All of the data about your files is stored in the catalog, but not the image files themselves. The organization of your file structure, the naming of files, and the metadata you add are all completely up to you.

Create an organization that works for you and stick with it. Lightroom will assist you by managing all the data the way you want.

The image with this article is the one I referenced to show the location information Lightroom records. You can infer from the file path that it was shot in Tucumcari NM on Nov 10, 2023. It has nothing specifically to do with catalogs, I just decided to show what that image was to make it real..

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