Override field module function in custom module? I want to override field_sql_storage_field_storage_write(), defined in /modules/field/modules/field_sql_storage/field_sql_storage.module.

I tried with MYMODULE_field_storage_write_alter($entity_type, $entity, $op, $fields), but it doesn't work. 

How should I override that function?
You could try hook_field_storage_info_alter

Other candidates are


hook_field_insert
hook_field_update