Database: scholar
Question: When does Michael Stonebraker publish the GIS Database paper ?
SQL: select distinct t3.year from paperkeyphrase as t2 join keyphrase as t5 on t2.keyphraseid  =  t5.keyphraseid join paper as t3 on t3.paperid  =  t2.paperid join writes as t4 on t4.paperid  =  t3.paperid join author as t1 on t4.authorid  =  t1.authorid where t1.authorname  =  "michael stonebraker" and t5.keyphrasename  =  "gis database";