MySQL – Understanding innodb_file_format Barracuda

InnoDB has Limitations on row lengths and BLOBs. According to the MySQL Documentation:

The maximum row length, except for variable-length columns (VARBINARY, VARCHAR, BLOB and TEXT), is slightly less than half of a database page. That is, the maximum row length is about 8000 bytes. LONGBLOB and LONGTEXT columns must be less than 4GB, and the total row length, including BLOB and TEXT columns, must be less than 4GB.

If a row is less than half a page long, all of it is stored locally within the page. If it exceeds half a page, variable-length columns are chosen for external off-page storage until the row fits within half a page, as described in Section 14.3.12.2, “File Space Management”.

Although InnoDB supports row sizes larger than 65,535 bytes internally, MySQL itself imposes a row-size limit of 65,535 for the combined size of all columns:

mysql> CREATE TABLE t (a VARCHAR(8000), b VARCHAR(10000),
-> c VARCHAR(10000), d VARCHAR(10000), e VARCHAR(10000),
-> f VARCHAR(10000), g VARCHAR(10000)) ENGINE=InnoDB; ERROR 1118 (42000):
Row size too large. The maximum row size for the used table
type, not counting BLOBs, is 65535. You have to change some columns to
TEXT or BLOBs

See Section E.10.4, “Limits on Table Column Count and Row Size”.

You are going to have to recreate the mysqldump so that the Storage Engine is Specified. Perhaps just drop the --compatible=mssql from the mysqldump command. The end result is the that the table will remain a MyISAM table when being imported into MariaDB.

This is just a guess but look at the error message you posted. If a BLOB prefix is 768 bytes and you have 10 BLOBs, that 7680 bytes. That leaves you with 320 bytes. If the remaining datatypes exceed 320 bytes, then it is impossible to convert to InnoDB.

Since a TEXT column is the variant of a BLOB, converting to TEXT does nothing since the storage requirements for TEXT and BLOB field are identical.

This is a very tough question to answer simply because you are going beyond InnoDB current limits.

Your question is not by any means unique. This has been addressed here before

• By Me, Aug 14, 2012 : error 1118: row size too large. utf8 innodb
• By Bill Karwin, Oct 06, 2011 : InnoDB create table error: "Row size too large"

I would also look into the character set you are currently using.

Bill Karwin said it best in his last paragraph

I also have to comment that I've never seen a well-designed table exceed the row size limit. It's a strong "code smell" that you're violating the repeating groups condition of First Normal Form.

You are going to have to define a better design. No business reason can ever justify it. Why?

Back on July 20, 2011, I answered this question: Too many columns in MySQL

I personally eyewitnessed this

In my earlier days as a developer, I worked at a company back in 1995 where DB2 was the main RDBMS. The company had a single table that had 270 columns, dozens of indexes, and had performance issues retrieving data. They contacted IBM and had consultants look over the architecture of their system, including this one monolithic table. The company was told "If you do not normalize this table in the next 2 years, DB2 will fail on queries doing Stage2 Processing (any queries requiring sorting on non-indexed columns)." This was told to a multi-trillion dollar company, to normalize a 270 column table. How much more so a 2000 column table.

A table with 300 TEXT columns is asking for same kind of trouble.

SUMMARY : Bill Karwin said it before and I agree: REDESIGN THE TABLE. That will circvumvent the row length issue for sure.