read pdf content from BLOB in MySQL

i have developed a system which parses and stores emails into a MySQL database. I save the attachments as an array of objects in JSON into a MEDIUMBLOB field. Everything works almost as expected. At least when saving. When i try to read the attachments i only get back the images, but not the pdf file.

The BLOB has the following ‘dummy’ content:

"filename":"img1.png", "ext":"png", "type": "image/png", "size":4096, 
"dispo":"inline", "cid":"[email protected]", "content":"base64_encoded binary- 
"filename":"pdf1.pdf", "ext":"pdf", "type": "application/pdf", 
"size":4096, "dispo":"attachment", "cid":null, 
"content":"base64_encoded binary-data"

The attachments are written as follows: json_encode($attachmentsDB,JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT).

I debugged, but somehow when i fetch data BLOB from the DB – in this case – the last element = the pdf-file is not returned. Only the preceding image files.

When i hardcode the data and try my code it works perfectly. The data isn’t truncated either.

It seems that it’s not a memory problem

If anybody could give me a hint please… ?

Many thanks in advance


As mentioned by @Shadow:

Mediumblob is up to 16MB only. Base64 drastically increases the size of the data, so there may be some data truncation even if the original binary size is below 16MB. Pls include the code that stores and retrieves the files from the database.

i modified the field to LONGBLOB and now it seems to work fine! 🙂