We noticed this bug in Redshift. It then occurred to me that this may very well be a PG bug since Redshift is based on PG. Reproduced it in Version 11.5 create table bugtest (fld1 char(1)) ; insert into bugtest values('a'); insert into bugtest values('b'); insert into bugtest values('c'); insert into bugtest values('d'); insert into bugtest values('e'); select count(*) from bugtest where fld1 in ('a','b','c', 'd','e'); -> produces 5 as output. So far so good. Now check this: select count(*) from bugtest where fld1 in ('a','b','c' 'd','e'); Note the missing comma after 'c'. PG takes it a syntactically right SQL and gives 3 as output. In SQLServer it errors out SQL Error [102] [S0001]: Incorrect syntax near 'd'. Can't believe this bug was never found before. We ended up wasting lot of time to figure this out.