Database: scholar
Question: How many papers did David M. Blei publish at AISTATS ?
SQL: select distinct count ( t3.paperid ) from venue as t4 join paper as t3 on t4.venueid  =  t3.venueid join writes as t2 on t2.paperid  =  t3.paperid join author as t1 on t2.authorid  =  t1.authorid where t1.authorname  =  "david m. blei" and t4.venuename  =  "aistats";