I could not find storage requirements for JSON type columns in MySQL documentation

How much storage space allocated for JSON type column in InnoDB? Are JSON columns the same as BLOB?

  • 2
    I don't know the answer (hence I am writing a comment), but I would expect it to be on the order of magnitude as the number of characters in the JSON. Suggest filling a documentation bug at bugs.mysql.com .
    – Rick James
    Jan 24, 2017 at 17:00
  • @RickJames per your suggestion I opened a bug. I hope they will eventually provide the info.
    – olegsv
    Jan 25, 2017 at 15:27
  • Please post the link to the bug report.
    – Rick James
    Jan 25, 2017 at 17:58
  • bugs.mysql.com/bug.php?id=84669
    – olegsv
    Jan 26, 2017 at 18:25

1 Answer 1


JSON have optimised storage format compare with old method (save as TEXT), but no any other information You will not find,

because JSON size always depends from JSON data, some of them could be more optimised, some less, plus different length, plus ...

Optimized storage format. JSON documents stored in JSON columns are converted to an internal format that permits quick read access to document elements. When the server later must read a JSON value stored in this binary format, the value need not be parsed from a text representation. The binary format is structured to enable the server to look up subobjects or nested values directly by key or array index without reading all values before or after them in the document.

It is like - what zip archiver ratio? Is it same for txt and jpg?

some more information there - https://dev.mysql.com/doc/refman/5.7/en/json.html

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.