Tracking down SQL errors?

Hi,

Using EE 2.11.0, PHP 5.5.32, and MySQL 5.7.

While diagnosing a different application that was having problems, we noticed that we were getting a lot of errors of this type:

2016-03-21T20:31:56.871657Z 209525 [Warning] InnoDB: Cannot add field wd_field_id_120_233 in table tmp.#sql_7b9_0 because after adding it, the row size is 8145 which is greater than maximum allowed size (8126) for a record on index leaf page.

Focused as we were on that application, we didn’t think about the fact that field_ids are really common in EE, and indeed when we isolated the problem we came to realize it was something wrong with our ExpressionEngine install.

We’ve followed recommended steps at http://stackoverflow.com/questions/15585602/change-limit-for-mysql-row-size-too-large – increased innodb_log_file_size and switched to the Barracuda format (have not turned on compression, though) – but apparently the errors still crop up.

Does anyone know how we can track down what’s causing this problem?