Hi. I want add Zigzag Merge join to Index Nested Loops Join alghoritm. http://www.cs.berkeley.edu/~fox/summaries/database/query_eval_5-8.html Which files are responsible for Index nested loops join ? (not simple nested loops join which has double foreach in nodeNestloop.c) nodeIndexscan.c? nodeIndexonlyscan.c? Best Regards Tom