Not all duplicates cleared when the grid data is persisted in a postgres based datastore

Relating to https://tablegrid.atlassian.net/browse/IGRID-1601

 Problem

When using the 'Clear all duplicates' tool on a grid, duplicates might not be cleared correctly

Open

Reason 

It happens only when

• The grid is persisting data in a postgres database

• The grid contains one or more columns of type 'textarea'