In older versions of 4D it was possible to create a field with 'unique' but not indexed. This causes 4D to have to do full table scans for every insert/update in order to validate uniqueness. In a large table, this is a huge performance problem. Clearly a competent developer who understands the basics of how databases work would never do this on a large, frequently updated table, but 4D still let you fall into that trap.
Starting with 13.5, 4D no longer allows this. -- Jeffrey Kain [email protected] > On Feb 4, 2017, at 2:14 PM, Arnaud de Montard <[email protected]> wrote: > > When I check the unique property of a field, 4D adds an index to that field. > Same when I define a primary key. So I'm wondering if being unique is an > index property instead of a field property… But in system tables, that > property exists twice: ********************************************************************** 4D Internet Users Group (4D iNUG) FAQ: http://lists.4d.com/faqnug.html Archive: http://lists.4d.com/archives.html Options: http://lists.4d.com/mailman/options/4d_tech Unsub: mailto:[email protected] **********************************************************************
