Storing image in database directly or as base64 data?

Question

The common method to store images in a database is to convert the image to base64 data before storing the data. This process will increase the size by 33%. Alternatively it is possible to directly store the image as a BLOB; for example:

$image = new Imagick("image.jpg");
$data = $image->getImageBlob();
$data = $mysqli->real_escape_string($data);
$mysqli->query("INSERT INTO images (data) VALUES ('$data')");

and then display the image with

<img src="data:image/jpeg;base64,' .  base64_encode($data)  . '" />

With the latter method, we save 1/3 storage space. Why is it more common to store images as base64 in MySQL databases?

UPDATE: There are many debates about advantages and disadvantages of storing images in databases, and most people believe it is not a practical approach. Anyway, here I assume we store image in database, and discussing the best method to do so.

Answer 1

I contend that images (files) are NOT usually stored in a database base64 encoded. Instead, they are stored in their raw binary form in a binary column, blob column, or file.

Base64 is only used as a transport mechanism, not for storage. For example, you can embed a base64 encoded image into an XML document or an email message.

Base64 is also stream friendly. You can encode and decode on the fly (without knowing the total size of the data).

While base64 is fine for transport, do not store your images base64 encoded.

Base64 provides no checksum or anything of any value for storage.

Base64 encoding increases the storage requirement by 33% over a raw binary format. It also increases the amount of data that must be read from persistent storage, which is still generally the largest bottleneck in computing. It's generally faster to read less bytes and encode them on the fly. Only if your system is CPU bound instead of IO bound, and you're regularly outputting the image in base64, then consider storing in base64.

Inline images (base64 encoded images embedded in HTML) are a bottleneck themselves--you're sending 33% more data over the wire, and doing it serially (the web browser has to wait on the inline images before it can finish downloading the page HTML).

On MySQL, and perhaps similar databases, for performance reasons, you might wish to store very small images in binary format in BINARY or VARBINARY columns so that they are on the same page as the primary key, as opposed to BLOB columns, which are always stored on a separate page and sometimes force the use of temporary tables.

If you still wish to store images base64 encoded, please, whatever you do, make sure you don't store base64 encoded data in a UTF8 column then index it.

Answer 2

• Pro base64: the encoded representation you handle is a pretty safe string. It contains neither control chars nor quotes. The latter point helps against SQL injection attempts. I wouldn't expect any problem to just add the value to a "hand coded" SQL query string.

• Pro BLOB: the database manager software knows what type of data it has to expect. It can optimize for that. If you'd store base64 in a TEXT field it might try to build some index or other data structure for it, which would be really nice and useful for "real" text data but pointless and a waste of time and space for image data. And it is the smaller, as in number of bytes, representation.

Answer 3

Just want to give one example why we decided to store image in DB not files or CDN, it is storing images of signatures.

We have tried to do so via CDN, cloud storage, files, and finally decided to store in DB and happy about the decision as it was proven us right in our subsequent events when we moved, upgraded our scripts and migrated the sites serveral times.

For my case, we wanted the signatures to be with the records that belong to the author of documents.

Storing in files format risks missing them or deleted by accident.

We store it as a blob binary format in MySQL, and later as based64 encoded image in a text field. The decision to change to based64 was due to smaller size as result for some reason, and faster loading. Blob was slowing down the page load for some reason.

In our case, this solution to store signature images in DB, (whether as blob or based64), was driven by:

1. Most signature images are very small.
2. We don't need to index the signature images stored in DB.
3. Index is done on the primary key.
4. We may have to move or switch servers, moving physical images files to different servers, may cause the images not found due to links change.
5. it is embarrassed to ask the author to re-sign their signatures.
6. it is more secured saving in the DB as compared to exposing it as files which can be downloaded if security is compromised. Storing in DB allows us better control over its access.
7. any future migrations, change of web design, hosting, servers, we have zero worries about reconcilating the signature file names against the physical files, it is all in the DB!

AC