Dear Sellacious dev team,
Finally I found a problem with your code and my data. I'm using Sellacious v1.7.3 and the issue is not fixed in v1.6.0 or fixed another one as written here
https://www.sellacious.com/community-support/2472-__sellacious_cache_specifications-doesn-t-exis
The problem is following: I did a number of product attributes and placed data to them. From time to time I catch an error that table named after ..._sellacious_cache_specifications doesn't exist.
The problem is in the cache table creating algorithm which is programmed in the Specifications.php file. I caught an error and found it in a log file as "Row size too large. The maximum row size for the used table type, not counting BLOBs, is 65535. This includes storage overhead, check the manual. You have to change some columns to TEXT or BLOBs".
Further study showed up that in this code
$lenSql = 'SELECT MAX(LENGTH(field_value)) FROM #__sellacious_field_values WHERE field_id = %d';
foreach ($fields as $field)
{
$len = $this->db->setQuery(sprintf($lenSql, $field->id))->loadResult();
$col = 'spec_' . $field->id;
$cmt = $field->title;
$cols[] = sprintf('%s VARCHAR(%d) NOT NULL DEFAULT %s COMMENT %s', $this->db->qn($col), $len + 1, "''", $this->db->q($cmt));
....
you do not check if full table row will exceed 65535 bytes. Next code makes a query to the database and throws an exception.
So I found a problem but do not have decision yet.